I’ve been testing one of these new IdeaPads, a small, thin model called the U110, that’s sized to be ideal for travelers. It looks nothing like a classic black ThinkPad. It even comes in red, has swirls etched into its case, and can supposedly log you in by recognizing your face using its built-in camera.

At the same time, I’ve been trying out another similarly sized little laptop, the U2E from Asus (23571.TWO), a Taiwan-based company whose products are relatively new to the U.S. This computer has its own distinctive design: It’s clad in real leather. It also has a camera, and it can be ordered with one of the new solid-state drives, which have no moving parts, instead of a hard disk.

Both of these small laptops are subnotebooks, meaning they weigh 3 pounds or less. Like many subnotebooks, they have small 11-inch screens and somewhat cramped keyboards. And, like most subnotebooks, they are costly — an $1,899 starting price for the Lenovo and $1,999 for the Asus.

Each can only be ordered with Microsoft’s (MSFT) Windows Vista operating system, which means you can practically walk your dog in the time it takes them to start up. Each has a standard battery so wimpy that it provides poor battery life, so both companies throw in bigger batteries that provide decent power, but make the computers larger and heavier.

I wish I could recommend a clear winner between these two contenders, but both are mixed bags. The IdeaPad is lighter, thinner, and has a slightly faster processor. The Asus has a built-in DVD drive, while the Lenovo’s is external. The Asus also has the new, faster “N” type of Wi-Fi networking, while the IdeaPad is stuck with the older, slower “G” type.

Lenovo’s small, thin IdeaPad model called the U110.

The IdeaPad has two big flaws, in my view. First, it has blown the biggest advantage of its sibling, the ThinkPad: a great keyboard. The IdeaPad keyboard has huge, flat keys with slick, shiny surfaces and almost no space between them. I found typing difficult with this setup. I asked two people who are faster typists than I am to try it: One liked it, one hated it. The IdeaPad also dispenses with the TrackPoint, the little pointing stick for moving the cursor that many ThinkPad lovers revere.

By contrast, the Asus U2E keyboard, while nothing to write home about, is more conventional and more usable, with traditional tapered keycaps that provide better key separation. The mouse buttons underneath the touch pad on the Asus, while thin, were sturdier than the ones on the IdeaPad, which had a cheap feel to me.

The second big flaw in the IdeaPad is its most hype-worthy feature: face recognition, which is meant to spare you the need to type in a password to log in. In a dozen tests, it recognized me only twice. I asked my wife to try it, and it never once recognized her. It did recognize a colleague successfully, but we tried it only once with her.

The Asus’s biggest flaw is its solid-state drive. It adds $700 to the price, for a total of $2,699, but is only 32 gigabytes in size, tiny by today’s standards. To compensate, Asus throws in an external hard disk, but that’s an inconvenient solution.

You can order the Asus with a standard 120-gigabyte internal hard disk for the $1,999 price, but that’s still $100 more than Lenovo charges for the IdeaPad with the same sized drive.

Each machine has three USB ports, a video-out connector, a slot for camera memory cards, and an ExpressCard slot, typically used for cellphone modems. Neither has a built-in cellphone data modem. The Asus has three gigabytes of memory, the Lenovo just two.

In my tough battery tests, where I turn off all power-saving features, turn on the Wi-Fi, and keep music playing constantly, the Asus got about 1.5 hours and the Lenovo a miserable one hour and three minutes. This means that, even with a more normal usage pattern, you’d be lucky to get two hours out of the IdeaPad and 2.5 hours from the Asus.

With the included bigger batteries, the IdeaPad clocked out at three hours and 10 minutes, which means you could probably stretch it to over four hours with more normal use. The Asus’s bigger battery delivered an excellent five hours and 29 minutes in my test, which points to nearly seven hours in more normal use. Asus says it has tweaked its machines to improve battery life somewhat.

However, while the jumbo battery on the IdeaPad barely protrudes from the machine, and keeps the weight under three pounds, the one on the Asus U2E is so huge it looks like a tumor and pushes the weight to 3.4 pounds, well above the subnotebook cutoff.

If you’re a frequent traveler, both of these models are worth considering, but each has its own flaws.

• Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

As always, this is a general guide aimed at mainstream, nontechnical consumers who dwell on common tasks such as email, instant messaging and surfing the Web; managing and lightly editing photos, videos and music; and using basic office applications. It is not intended for heavy gamers, video producers or corporate buyers.

There’s a vast variety of laptop models, but this guide is meant to cover the most common types of laptops, those with screens from about 12 inches to 17 inches, and weights ranging from around 2.5 pounds to 7 pounds.

For this column, I’m not including the category of tiny machines now called netbooks, with screens under 10 inches. I am also ignoring the huge, heavy laptops with screens larger than 17 inches that are primarily aimed at gamers.

Even the remaining mainstream machines range wildly in price, from bargain-basement models at $350 to high-end ones that can top $3,000. In my experience, the top brands for technology and reliability are Apple and Lenovo‘s ThinkPad line, but various models from Sony, Hewlett-Packard, Toshiba and Dell are also worth investigating.

So, here is a quick guide to the key factors you should consider when buying a laptop.

Size: If you are a constant traveler, think about the subnotebook models, which generally weigh 3 pounds or less. There are two types of these. The classic subnotebook has a small screen, 12 inches or less, and a cramped keyboard. This year, a new type emerged, with a full keyboard and a normal 13.3-inch screen packed into a thin, light body. There are two of these: the MacBook Air from Apple and the Lenovo ThinkPad X300. All subnotebooks are relatively costly, typically ranging from $1,500 to over $3,000.

If your laptop will mostly stay at home, the office, or in class, a 5-7 pound machine with a screen of either 13.3 inches or 15.4 inches is the best bet. A well-equipped model in this class is likely to run you between $800 and $1,200. Typical models in this class are the Dell Inspiron 1525, the HP dv6700 and the Apple MacBook.

Windows vs. Mac: This is the eternal question. In my view, Apple’s Leopard operating system is faster, better and far less prone to malicious software than Microsoft’s Vista operating system. And the Mac laptops also come with better built-in software. The $1,099 MacBook is a solid, fairly priced machine, and the $1,999 MacBook Pro is even better. Both also can run Windows.

But Windows laptops are often less expensive, tend to have a greater variety of ports and slots, and come in more styles and sizes.

Apple’s MacBook

Operating system: If you are buying a Windows laptop, be aware that Vista is slower than Windows XP, in my experience, and still has compatibility issues with add-on hardware and software. If you’d prefer to stick with XP, you will find that many fewer models are available with it. And Microsoft has decreed that after June 30, mainstream, name-brand laptops will no longer come pre-equipped with XP.

Video: I recommend getting an LED-powered screen, which is brighter and saves power. Also, if you are choosing Vista, or if you do a lot of converting video for use on portable devices, consider getting a laptop with a separate video card inside that has its own memory.

Memory: If you’re buying an Apple laptop, two gigabytes of memory is plenty. If you’re using Vista Home Premium, I’d consider three gigabytes for best performance.

Processor: Any dual-core processor will be fine. Don’t pay a penny extra for faster processor speed.

Storage: In a mainstream laptop that will be your main computer, look for a 160-gigabyte hard disk or larger. A new kind of storage, called SSD, or solid state disk, is now available. But it is still way too costly for most users, and at the moment is available only in smaller capacities.

Battery life: Many laptops today rarely spend time away from an electrical outlet. But if yours will, look for a battery life of at least three hours between charges.

Wireless: Make sure your new laptop has the new, faster “N” version of Wi-Fi built in. Many cheaper laptops don’t. You can also get a cellphone modem built in, but they are costly and carry a monthly fee. You can always add an external cellphone modem later.

Other features: A built-in camera and microphone can be quite useful, and so can a feature on some Windows machines that allows you to play music and videos without fully booting up the computer.

Don’t let yourself be swayed by sales pitches, or by fanaticism for or against Windows or the Mac. Think hard about how you use your computer and what your budget will allow, and stick to those priorities.

• Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

But this isn’t the much-touted Apple MacBook Air, introduced last month with all those qualities. Instead, it’s a new ThinkPad from Lenovo, the X300. While the two machines are both impressive products, they are different in key respects.

I’ve been testing the ThinkPad X300 and I have found it to be a solid, innovative laptop that will be perfect for many mobile PC users. It isn’t as sexy or inexpensive as the MacBook Air, but it has numerous features the Apple lacks, especially a wide array of ports and connectivity options, a built-in DVD drive and a removable battery.

I can recommend the X300 for road warriors without hesitation, provided they can live with its two biggest downsides: a relatively paltry file-storage capacity and a hefty price tag. This ThinkPad starts at $2,476 for a stripped-down model and at $2,799 for a preconfigured retail version with a half-size battery. The configuration I expect to be the most popular, with a full-size battery and DVD drive, is about $3,000.

The key factor in both of these downsides is the solid-state drive, or SSD, which replaces the hard disk. The SSD is fast and rugged, but today it can hold only a cramped 64 gigabytes of files and is very costly. Apple offers a MacBook Air version with the same solid-state drive for a similar high price. But Apple also has a much more affordable $1,799 model with an 80-gigabyte standard hard disk. Lenovo doesn’t.

Lenovo’s ThinkPad X300

The X300, due to go on sale next week at lenovo.com and at a few retailers, isn’t as thin as the MacBook Air. In fact, at its thinnest point it is almost as thick as the Apple is at its thickest point. And when the new ThinkPad is ordered in what are likely to be its most common configurations, it is heavier than the three-pound Apple and, in fact, fails to make the three-pound cutoff that typically denotes a “subnotebook.” Only one configuration breaks that barrier, at 2.93 pounds, and it is the stripped-down model with just a half-size battery and no DVD drive.

But the X300, which will come with either Windows Vista or Windows XP, is still very thin and light. It’s under an inch thick and even at its heaviest is only 3.5 pounds. Yet, like the Apple, it packs in a widescreen 13.3-inch display and a full-width keyboard.

Plus, Lenovo has used that extra thickness to good advantage. While the MacBook Air’s extreme thinness makes it gorgeous, it left no room for an Ethernet jack, a removable battery, a built-in DVD drive or a cellphone modem. The X300 has all these things, either standard or as options, plus three USB ports, compared with just one for the Apple. The Lenovo even offers GPS location-finding, the ability to connect to new wireless USB devices and future support for a forthcoming wireless network standard called WiMax.

The ThinkPad has another advantage: Even though its screen is the same size as the Apple’s, it is higher resolution, so more material can be seen without scrolling. Some people find that higher-resolution screens make text too small to read easily, but I didn’t experience any such problem on the X300.

In my tests, the X300 performed very well, even though it has a relatively slow processor, slower than the MacBook’s.

But the ThinkPad’s battery life was only fair, and was inferior to the Apple’s. In my tough test, where I turn off all power-saving features, set the screen to maximum brightness, turn on Wi-Fi and run a repeating play list of music, the X300 lasted three hours and five minutes. That was 24 minutes less than the comparable MacBook Air. And this was on the $3,000 configuration with a full-size battery and a DVD drive. The more basic models, with a half-size battery, would last only half as long, according to Lenovo.

MacBook Air

In more normal use, the model I tested would likely last under four hours on a charge, and the base models maybe two, compared with about 4.5 hours for the Mac.

I also tested another version of the ThinkPad, which substitutes a second, half-size battery for the DVD drive. It got five hours and 15 minutes, which means you could likely get 6.5 to seven hours in normal usage. That model costs around $2,850.

There are two more factors worth mentioning. I believe that both the Mac operating system and the software that comes with it are superior to the Windows operating system and built-in software offered on the ThinkPad. And the Mac isn’t susceptible to the vast majority of viruses and spyware, and doesn’t require third-party security software.

Also, the ThinkPad’s screen, when opened, stands significantly higher than the Mac’s, so it is less usable in a coach seat on an airplane when the person in front of you reclines.

If you’re happy with Windows, can afford the price tag, and value the many ports and connectivity options Lenovo has packed in, the thin and rugged X300 is a great choice. It’s a notable engineering accomplishment.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Only a month or so after Apple announced its MacBook Air laptop, which it calls the world’s thinnest laptop, Lenovo is about to spring its own super-skinny machine: the ThinkPad X300. Here’s a sneak peek. My full review will appear after I have fully tested this unusual new laptop, which I expect to be of great interest to road warriors.

Like the MacBook Air, this is a rare small laptop that is built around a full 13-inch-wide screen display and a full keyboard, rather than the little screens and cramped keyboards common in subnotebooks. And, like the Air, it offers a fast, rugged solid-state drive instead of a hard disk.

But, unlike the Apple, Lenovo’s new skinny ThinkPad comes with a hefty complement of ports and features, some of the very things critics complained Apple left out. It has a built-in DVD drive, removable battery, three USB ports, and a wired Ethernet networking jack. Inside, in addition to Wi-Fi, it can be ordered with a built-in cellphone modem and even GPS. It comes with either Windows Vista or Windows XP.

Sporting the traditional ThinkPad black slab design, the X300 isn’t as skinny or sexy as the Apple, but it’s still very slender and attractive, at under an inch thick. Also, unlike the Apple, most of the ThinkPad’s configurations are a bit heavier than the 3-pound weight that traditionally denotes a subnotebook. But it still feels very light to carry around, at 3.12 pounds with the standard battery and DVD drive.

The biggest downsides to the new ThinkPad X300 are price and limited storage capacity. Unlike the Apple, which can be ordered with a higher-capacity, lower-priced hard disk, the new ThinkPad will only be available with the expensive, limited capacity solid-state drive. So it will start at between $2,500 and $2,800–up to $1,000 more than the Apple’s base price–and will be limited to a paltry 64 gigabytes of storage.

The new aluminum-clad MacBook Air, which I’ve been testing for several days, is billed as the world’s thinnest notebook computer. Its thickest point measures just three-quarters of an inch, which is slimmer than the thinnest point on some other subnotebooks. And it employs some innovative software features, such as fingertip gestures for its touchpad that are similar to those on Apple’s iPhone.

Apple refused to make the most common compromise computer makers employ to create their littlest laptops. Other subnotebooks — a category generally defined as weighing three pounds or less — have screens of just 10 to 12 inches and compressed keyboards. The three-pound MacBook Air, by contrast, features a 13.3-inch display and a full-size keyboard.

It’s impossible to convey in words just how pleasing and surprising this computer feels in the hand. It’s so svelte when closed that it’s a real shock to discover the big screen and keyboard inside.

But there’s a price for this laptop’s daring design: Apple had to give up some features road warriors consider standard in a subnotebook, and certain of these omissions are radical. Chief among them is the lack of a removable battery. So, while the MacBook Air will be a perfect choice for some travelers, I can’t recommend it for all. It really depends on your style of working on the road and what features you value most.

The MacBook Air, which will be available next week, costs $1,800 with an 80-gigabyte hard drive and a generous two gigabytes of memory. A second model, with a faster, cutting-edge, 64-gigabyte, solid-state drive and a slightly speedier processor, costs a whopping $3,100. The $1,800 price for the main model isn’t unusual in subnotebooks, which can easily top $2,000, although some competitors cost less.

In my tests, the MacBook Air’s screen and keyboard were a pleasure to use. The machine felt speedy, even with multiple programs running. And the laptop has the same Leopard operating system, superior built-in software, and paucity of viruses and spyware that I believe generally give the Mac an edge. I was able to install and run Windows XP using the third-party Parallels software.

But then there are those trade-offs. The sealed-in battery means you can’t carry a spare in case you run out of juice, and you have to bring it to a dealer when you need a new one. There’s no built-in DVD drive. The thin case can’t accommodate a larger internal hard disk. And the machine omits many common ports and connectors.

The MacBook Air

There’s no Ethernet jack for wired broadband Internet connections and no dedicated slot for the most common types of external cellphone modems. That means that out of the box, the MacBook Air has only one way to get on the Internet — through its fast, built-in Wi-Fi connection. If you’re out of Wi-Fi range, you’re out of luck, unless you buy an optional, $30 add-on Ethernet connector or a cellphone modem that connects via USB.

In fact, the MacBook Air has only three connectors: a headphone jack, a single USB port and a port for connecting an external monitor.

That single USB port is a problem, because so many peripherals use USB. You can buy a tiny, cheap USB hub that adds three more ports, but that’s yet another item to carry.

The lack of a DVD drive is partly solved by some clever software Apple included that lets you “borrow” the DVD drive on any other Mac or Windows PC on your network, so you can transfer files or install new software from a CD or DVD. This worked fine in my tests, in which I installed several new programs from CDs on remote computers, but it requires disabling third-party firewalls on Windows machines. It also doesn’t work for installing Windows on your Mac, for watching DVDs, or for playing or importing music. For those tasks, you need an external DVD drive. Apple sells one for $99.

In my standard battery test, where I disable all power-saving features, set the screen brightness at maximum, turn on the Wi-Fi and play an endless loop of music, the MacBook Air’s battery lasted 3 hours, 24 minutes. That means you could likely get 4.5 hours in a normal work pattern, almost the five hours Apple claims.

But the MacBook Air has another downside: its screen height. Because of the larger screen, the lid stands higher when opened than on most other subnotebooks. So it isn’t as usable as some competitors when the seat in front of you in coach on a plane is reclined.

If you value thinness, and a large screen and keyboard in a subnotebook, and don’t watch DVDs on planes or require spare batteries, the MacBook Air might be just the ticket. But if you rely on spare batteries, expect the usual array of ports, or like to play DVDs on planes, this isn’t the computer to buy.

• Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Unfortunately, every attempt at this concept has included too many compromises to justify their often surprisingly high prices. I’ve been testing the latest effort at such a device, the Eee PC, from a Taiwan-based laptop maker called Asus. It does better than some of the earlier contenders in certain respects, such as text entry and price. But it still is likely to prove unsatisfying for many road warriors.

Asus doesn’t even call the Eee a computer, referring to it as a “mobile Internet gadget.” Instead of using Microsoft Windows as its operating system, the Eee uses a specially designed version of the open Linux operating system, and comes preloaded with a variety of open-source programs for Web browsing, performing office tasks, playing music and videos, running games and managing photos.

The Eee has a much smaller footprint than even the subnotebook category of laptop, such as the much-publicized MacBook Air unveiled by Apple this week (which I’ll review after I have thoroughly tested it), or subnotebooks from Sony and Lenovo. It weighs a mere two pounds, is just under 9 inches wide and just over 6 inches deep. It is thicker than the new Apple and some other subnotebooks, ranging from 0.79 inches at its thinnest point to 1.26 inches at its thickest. The overall effect is small, but stubby.

The Eee’s price is only a fraction of what typical subnotebooks cost — from $300 to $500, depending on configuration. The model I tested, called the Surf, is the base $300 entry. With its pastel blue lid, and tiny size, it looks like something Barbie might use. But it can perform real work, even though it comes with only 512 megabytes of memory and a scant two gigabytes of storage space.

One reason the device costs and weighs so little is that there is no hard disk. Files are stored on memory chips. It is possible to add storage by popping in a flash memory card or by connecting a USB drive to one of the three USB ports.

Unlike some computers in its category, the Eee isn’t a tablet. It takes the clamshell form of a traditional laptop and, when opened, reveals a full, if very cramped, keyboard. By including a real keyboard and charging so little, Asus has overcome two of the problems that plagued Samsung’s Q1 ultramobile computer awhile back.

Asus Eee PC

The user interface on the Eee is simple and clear. It consists of tabs labeled Internet, Work, Learn, Play, Settings and Favorites. Each tab contains large, colorful icons. For instance, the Work tab includes icons for Documents, Spreadsheets and Presentations. These tabs lead to various modules of the free OpenOffice suite, a competitor to Microsoft Office.

The Internet tab has various icons, such as Web Mail, Web and Wikipedia, that open the Firefox Web browser. You get to this tabbed screen by just pressing a Home button.

In my tests of the Eee, I was able to use all manner of Web sites, send and receive Web-based email, compose and open Microsoft Word documents from other computers, play music, and view photos.

So, with a low price, a small size, a real keyboard, and a clean user interface, what’s not to like about the Eee?

Well, for starters, its tiny 7-inch display is just too stingy for serious work. You can make up for a small screen size with high resolution, but the 800 by 480 resolution on the Eee — which can’t be changed — is so wimpy that very few lines of text can be seen at any one time. This means you’ll have to do so much scrolling, it’s likely to drive you crazy.

Also, the lack of a hard disk, and the relative paucity of truly simple Linux software, means that most nontechie users will be stuck with the included programs, which can’t be removed and which don’t include a calendar or contacts program, or even an email program. You can only use Web-based email.

And just below the Eee’s simplified user interface lurks the complicated terminology and software design characteristic of Linux. Some error messages I saw were indecipherable.

Beyond that, many of the Linux programs included were far cruder and harder to figure out than, say, Microsoft’s Photo Gallery or Apple’s iTunes. The Eee wouldn’t automatically reconnect to a known wireless network, and it wouldn’t recognize my Kodak digital camera.

Some of these problems can be solved if you install Microsoft Windows XP on the Eee. Asus includes instructions on doing so. But you have to supply your own copy of Windows.

The Eee is a valiant effort, but it still has too many compromises to pry most travelers away from their larger laptops.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Now, to what could these banners possibly be referring? Streaming iTunes movie rentals to the Apple TV? A genetically modified iVirus? The iSmell? A featherlight subnotebook? Or something else entirely? Say a WiMax-enabled MacBook Pro?