The first approach uses a feature called Boot Camp that comes free on every new Mac. Using Boot Camp, the entire Mac is turned into a Windows PC, with the full capabilities and speed of a standard Windows machine. No trace of the Mac operating system is left running. The downside is that you can’t run Windows and Mac programs side by side.

The second approach uses one of two third-party programs to create a virtual Windows PC inside your Mac. This faux Windows machine runs at normal speeds and can operate simultaneously with the Mac’s own operating system. Programs native to each operating system can run side by side. The downside is that, because Windows doesn’t get complete control of the computer’s hardware, it isn’t quite as fast as in Boot Camp, and a few of its functions, like 3D graphics, don’t work as well.

This latter method is enabled by two excellent, closely matched $80 programs: Parallels, from a Swiss-based company of the same name, and Fusion, from VMWare, a U.S. company. It is Fusion that just got better, because VMWare just issued version 2.0 of the product with lots of new features, some of which let it catch up to the older Parallels and some of which push it ahead.

I’ve been testing Fusion 2.0 for a couple of weeks on two different Macs, and using it to run both Windows XP and Windows Vista. My verdict is that while you won’t go wrong with Parallels, Fusion edges it out as the better product.

The new Fusion 2.0 is a free upgrade for owners of version 1.0. It can be obtained at vmware.com/mac and at various retailers.

Like Boot Camp and Parallels, Fusion requires you to obtain and install a fresh, boxed, full version of Windows on your Mac. But once you’ve done that, your Mac becomes two computers in one. If you need to run programs that are available only on Windows, you can do so with ease.

For instance, as I write this column on a MacBook pro laptop, using a Macintosh word processor, I am using Fusion 2.0 to simultaneously run Google’s new Chrome browser, which is so far available for Windows only. I can switch between the two with a couple of keystrokes and copy text from one to the other.

Like Parallels, Fusion allows you to run Windows programs in one of three ways. You can see the entire Windows desktop, with Windows programs running within it, inside its own window on your Mac. Or, using a feature called “Unity,” each Windows program can float free, as if it were just another Mac program, with the Windows desktop invisible. If you minimize a Windows program, it disappears into an icon in the Mac’s Dock, just as Mac programs do.

Finally, you can devote the entire screen to the Windows desktop and hide the Mac operating system entirely.

Parallels can also do these things. Both programs can now also “mirror” your most common Windows and Mac file folders so that, for instance, all of the files in your Mac’s Pictures folder also appear in the My Pictures folder in Windows XP. This is a new addition to Fusion, as is the ability to take multiple “snapshots” of your Windows virtual machine, so if something goes wrong, you can roll back to a previous state when things were stable.

But Fusion has some other features Parallels lacks. For example, it allows you to automatically take those protective snapshots at timed intervals. It also permits you to completely customize keyboard commands so that the same common key combinations work in both Windows and Mac programs. It allows the faux Windows machine to take full advantage of multiple monitors, if you have them.

Fusion also uses a more modern and capable version of the proprietary 3-D graphics system in Windows, called DirectX. That means some Windows-only games and other programs that won’t work in Parallels will work in Fusion. I successfully tested two such programs, both from Microsoft: Worldwide Telescope and Photosynth.

And, in my experience, Fusion is a bit faster than Parallels. Both programs put a strain on your Mac when performing major tasks, like starting up or shutting down Windows. But Fusion seems to affect the Mac less. And, unlike Parallels, it can make Windows quicker by optionally assigning it control of the multiple “cores” in most modern processor chips.

Fusion also offers a one-year free subscription to Windows security software, while Parallels offers only a six-month subscription.

However, Fusion has its limits. Like Parallels, it cannot run the 3-D visual effects in Windows Vista. And, in my tests, it wouldn’t allow Windows running on one of my Macs to use the printer that was configured on the Mac, although that feature did work on my other test Mac.

In my view, Fusion is now the better choice for running Windows on a Mac virtually.

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

Write to Walt Mossberg at mossberg@wsj.com

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability.

I am going to start college in the fall and I need a laptop. Uncle Jim, who is a Mac addict, is making an argument for a MacBook with Parallels 3.0 and Windows XP installed. He said that way I would have the best of both worlds. My mom is looking at the price. She said we could get a PC for less money but I want to make sure we’re making the right decision. If money is not an issue, what is your recommendation?

Both your mom and your uncle are correct. You can indeed get a decent laptop from Dell or Hewlett-Packard for less than the $1,099 that Apple’s least expensive Mac laptop, the MacBook, costs. But, in my view, the Mac has a better, faster operating system, better built-in software, and is far less likely to expose you to viruses and other malicious software. Plus, the MacBook itself is a sturdy piece of hardware. And there’s a very good Mac version of Microsoft Office that is fully compatible with files created on the Windows version.

Your uncle is also correct that Macs can run Windows, and Windows software, quite well. However, the solution he suggests, using the Parallels software, which enables Windows use on a Mac, will add significantly to the price. Parallels costs around $60, and you also must buy a full, boxed edition of Windows XP or Vista. While prices for Windows vary, this full version (not an upgrade version) of XP can cost nearly $200, and Vista typically costs more.

So, if money really isn’t an issue, I recommend the MacBook. But, since that is rarely the case in real life, you might want to weigh the cheaper alternatives more carefully. Or, if you do buy the MacBook, I’d hold off on the Windows installation until and unless you find you need Windows programs that have no counterpart on the Mac. The average undergraduate likely won’t.

I am dissatisfied with my Internet service provider and I would like to switch to another one. If I switch, can I keep the same email address? Do I have to keep paying the old ISP if I switch and keep the email address?

It depends on your ISP. If it is America Online, you will be able to drop AOL as your ISP and continue to use your aol.com address, regardless of which provider you use to access the Internet. But, in most cases, if you are using the email address provided by your ISP, you will have to relinquish it. However, I would suggest you consider obtaining an email account that isn’t tied to an ISP, so that, if you have to change ISPs again, it won’t disrupt your email. Among such email-only services are Yahoo Mail, Microsoft’s Windows Live Hotmail, and Google’s Gmail.

Your column last week concerned a navigation device called Dash Express that transmits the speed and location of your car to the company for traffic information purposes. But couldn’t this capability also be misused by the company to track a driver’s whereabouts, or even help issue speeding tickets?

Theoretically, yes. But the company, Dash Navigation, says it retains no personally identifiable information on its servers, and merely collects traffic data from participating cars anonymously. A company spokeswoman says: “If the FBI came in and asked us to find someone, we would have no way of locating an individual car.”

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I have a new H-P (HPQ) laptop and there are several preinstalled media-playing interfaces that have been foisted on me. Do I really need all of these interfaces? Can’t I just get all of this media to run through Windows Media Player or iTunes?

Since you weren’t specific, I don’t know what media software came with your new laptop. I’m sure some of it may have been redundant “craplets” — the unwanted software PC makers load onto their machines in order to collect a fee from the programs’ publishers. And you are correct that many of the most common audio and video file types can be handled by Windows (MSFT) Media Player and iTunes.

However, the Internet is full of media file types that are best played, or can only be played, in specialized software — either separate applications on your computer or online players that are enabled via your Web browser. So, over time, most users will collect additional players, or plug-ins for their Web browsers, that will supplement their main media-playing program. One way to see if the media software on your new computer is necessary is to test what types of files it handles. If you can open and play these same files in Windows Media Player or iTunes, and you prefer to do so, then you probably don’t need the added software.

If I am running Windows Vista on my iMac desktop using Parallels, will Apple’s Time Machine backup program automatically preserve the Windows hard disk, too?

Yes. Parallels, and its competitor, VMWare Fusion, create virtual Windows hard disks inside a Macintosh. When you are running Parallels or Fusion, Windows sees these virtual hard drives as if they are distinct physical disks. However, they are in fact just very large files on your Mac’s hard disk. So Apple’s (AAPL) Time Machine backup program treats them like any other file and backs them up. Time Machine can also restore these virtual Windows hard disks, in their entirety, just as it can restore other kinds of files.

There are some caveats, however. Time Machine treats each virtual Windows hard disk as a big, unified blob of data, so it cannot peer inside them to recover individual Windows files you may have accidentally deleted while running Windows programs. Also, if your virtual Windows hard disk is large, and it changes often, then using Time Machine to back it up may suck up a lot of space on your backup drive, as numerous archived versions of the file accumulate.

I currently have a DVD player and a large stack of DVDs that I play through my analog TV set. After the 2009 digital TV conversion, will I still be able to use my existing DVD player and play my existing DVDs, even if I buy one of the government-subsidized converter boxes?

The FCC says DVD players and other add-on gear “will continue to work, even if they are only analog-capable.” But it adds that “manufacturers are producing a number of different connectors to hook equipment together and improve picture and sound quality. Check with your equipment retailer to determine the types of connectors that will work with your equipment.”

In other words, while there’s no inherent conflict, it all depends on your particular DVD player, your particular TV set, and how you have them connected. The best thing to do is consult closely with the dealer or manufacturer selling the converter box so that you understand how it can coexist with your current DVD player setup, or how you might have to alter your current setup.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

My Dell PC, which is an older model running Windows XP, is very slow to boot up and I have a lot of icons on my desktop. Does the number of icons on my desktop have any relationship to the time it takes my PC to boot up?

Everything a PC must do when it starts up takes some time, and that includes drawing the desktop. A desktop with fewer icons takes less time to re-create. But, if your machine is “very slow” to start up, you may also have accumulated too many programs that are set to run upon start-up, including programs that you can’t see because they are launching behind the scenes. So, it would be wise to examine these programs and remove or disable as many as you can, keeping only those you really need. I suggest you obtain and run a program designed to help you do this. One good one comes from PC Magazine and is called Startup Cop Pro 3. It costs $8 and can be found at pcmag.com/downloads.

If I buy a Mac, can I move all the programs on my Dell over to the Mac?

While most common Windows file types can be copied to a Mac and will work there, the Windows programs on your Dell won’t run on the Mac’s operating system, so there’s no point in moving them to a Mac. There is one exception: If you plan to install and use Windows on your Mac, then your programs should run. However, some programs are designed to be locked to a single PC and won’t run on a second machine, even if it is a new Dell instead of a Mac running Windows. Furthermore, it can be difficult to move Windows programs to a new machine, because they are often made up of parts that are scattered in various places on the hard disk.

Two of the companies whose software allows you to run Windows on a Mac, Parallels and VMWare, do offer utilities that will copy the contents of a Windows PC to the portion of the Mac devoted to running Windows. The Parallels utility is called Transporter and the VMWare utility is called Converter.

Like many Internet users I have used Wi-Fi in airports, hotels and coffee bars. I have used it to access banking and brokerage accounts. Just how much at risk have I been? I am a Mac user. Am I more or less at risk than a Windows user?

No matter what kind of computer you use, there is some chance, however small, that a crook can intercept any data you send or receive over a public wireless network. So, my advice is to never, ever conduct financial transactions, or any highly sensitive communications, over any network you don’t control. It’s the same principle people should use when making voice calls on cellphones, which are easier to intercept than voice calls made on land lines. Be cognizant of the content of your communications of any kind when you are using public wireless networks.

You can find Mossberg’s Mailbox, and my other columns, online free at the new All Things Digital web site, http://walt.allthingsd.com.

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.

I couldn’t find any columns on products you recommend for monitoring kids’ Web access and installing parental controls. I recently purchased a new computer for my 9-year-old daughter. I want to make sure she can only access specific Web sites and I want to protect her from inappropriate spam and chatting.

If you have a computer running one of the newer versions of Windows or the Macintosh operating system, I recommend using the extensive parental controls that are now built right into those operating systems. While you can never underestimate the ingenuity of computer-savvy kids, these built-in controls, if properly used, are generally harder to evade than the ones provided by third-party software.

I did recently review these built-in parental controls, which appear in Windows Vista, and in the Tiger and Leopard editions of the Mac’s OS X operating system. You can find that column at: ptech.allthingsd.com/20070614.

I want to switch to a Mac, but my life is on Microsoft Outlook, which is only available on Windows. Is there a simple way to convert all of this data to programs on the Mac?

There is a $10 program that performs this task. It’s called O2M (Outlook to Mac) and is from a company called Little Machines. It can be downloaded at littlemachines.com, where you also will find details about the Mac programs with which it works. This is a Windows program, which transfers your Outlook data into files you copy to your Mac. You then manually import these files into your Mac programs.

According to the company, the program exports Outlook email, email attachments, contacts and calendar appointments and allows you to import this data into Apple’s built-in email, address book and calendar programs, as well as into Microsoft Entourage, and other third-party programs.

Another approach is to install Windows on your Mac, and keep running Outlook. If you do this using the Parallels or Fusion virtualization programs ($80 each, plus the cost of Windows,) you can run Outlook simultaneously with your Mac programs.

Does the new version of Microsoft Office for the Mac work on pre-Intel Mac models?

Microsoft says it does, though I didn’t test it on one of these older machines. According to Microsoft, the new Office 2008 runs on any Mac “with an Intel, PowerPC G5, or PowerPC G4 (500 MHz or faster) processor.” However, you also need a relatively recent version of the Mac operating system, either the new Leopard edition, or the latest update (called 10.4.9) of the Tiger edition.

You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital Web site, http://walt.allthingsd.com.

I have a Dell Dimension that is six or seven years old. Recently, the following message appears every time we start the computer: “WARNING: Dell’s monitoring system has detected that Drive 0 on the primary EIDE controller is operating outside of normal specifications. It is advisable to immediately back-up your data and replace your hard disk drive.” When we hit F1, the computer boots normally and functions fine. All our data is backed up on an external drive. What is going on? Is it time to bite the bullet and get a new computer?

I don’t know exactly what’s going on, but you should take the warning very seriously. It’s good that your data is backed up, but if your hard disk fails, you won’t be able to use the computer. Six or seven years is a long time to keep a computer, and hard disks do go bad. Just because it continues to work doesn’t mean it isn’t on the verge of sudden failure. At the very least, have Dell or a local technician diagnose the hard disk to see if it is a serious problem or one that can be easily fixed. If the disk is failing and you are otherwise perfectly satisfied with the computer, you can get a new drive that is much larger for a reasonable sum. You should also seriously consider buying a new computer, simply because everything else on your machine is also out of date and, as time goes on, you may find that more and more software and Web sites won’t work well with it.

Does either Parallels Desktop or VMWare Fusion support multiple virtual machines installed on a Macintosh — for instance, one running Windows XP and one running Windows Vista?

Yes. Both of them allow you to create multiple virtual computers, running Windows XP or Vista, older versions of Windows, or Linux, as long as your Mac has sufficient hard-disk space.

My Toshiba Satellite runs Windows XP Home, and it takes more than four minutes when starting up before I can open any programs. Is my computer running too many programs at start-up? If so, how can I view them and shut down the unnecessary ones?

That certainly could be one cause of the problem. It’s a common situation. To see what programs are set to run when you start up your computer and to turn off unwanted ones, you can use a somewhat geeky built-in program from Microsoft or simpler ones available from outside software vendors. To run the built-in program, go to the Start Menu, click “Run,” and in the blank box that appears, type in “msconfig.” This utility will let you turn on and off invisible start-up programs. Go to the tab marked “Startup” and check off any you don’t want. But be conservative — don’t turn off anything you don’t recognize and know is unneeded. A better solution, easier to use and with more information, is an $8 utility from PC Magazine called Startup Cop Pro. You can get it at: www.pcmag.com/article2/0,1759,2177188,00.asp. There are a number of similar programs that may work just as well, but unlike Startup Cop, I haven’t tested them and so can’t recommend them.

You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com