Microsoft tells me they don’t plan to issue a “recommended” hardware configuration for Windows 7, because the company believes there are too many varied uses to cover, and that any such statement would be too complex. The company also claims its minimum requirements have proved “generous” enough to cover most cases during the year of widespread testing of pre-release versions.

The minimum required hardware for Windows 7 is as follows: a 1 gigahertz or faster 32-bit or 64-bit processor; 1 gigabyte of memory for the 32-bit version of Windows 7 or 2 GB for the 64-bit version; and 16 GB of available hard disk space for 32-bit or 20 GB for 64-bit. In addition, Windows 7 will require a graphics card or integrated graphics chip that is compatible with at least Microsoft’s DirectX 9 graphics system and at least the 1.0 version of its graphics driver standard called WDDM (Windows Display Driver Model).

More details are at: windows.microsoft.com/systemrequirements. I would suggest at least doubling the memory Microsoft recommends, not because I believe the company is lying, but to give yourself some headroom as your needs and interests grow.

I have used Mac laptops for the past 15 years, and am in the market for a new machine. When it comes to computers, I’m not “the sharpest knife in the drawer,” and I only use my laptop for very simple, basic tasks. What new laptop would you recommend? I do not desire or need exceptional file storage, graphic capability or any other esoteric spec.

You could get a cheap, small Windows laptop called a netbook, which would meet your simple needs. Acer, Asus, Lenovo and others make good ones. But I’m not sure that’s the best choice for you, given your self-description. If you’re a longtime Mac user, and you are used to the Mac, I’d suggest you consider sticking with it, because any netbook would require you to learn a new operating system and new software, even for simple tasks. Mac laptops are excellent machines, with a great operating system and built-in software. The only negative is cost, which you didn’t mention as a criterion. Apple doesn’t make bargain laptops. The cheapest Mac laptop, at $999, costs about triple what you could pay for a netbook.

I would like to change my Internet Service Provider (ISP), but fear doing so, since the task of informing all my email contacts of the new address seems grossly laborious. Are you aware of any utility available that will perform this task accurately?

The only one I ever tested is called TrueSwitch, and is available at trueswitch.com. It is a service that copies all your email, address books, calendar entries and bookmarks from the old ISP to the new one; notifies everyone in your address book of your new email address; and even forwards email from your old address to your new one for 30 days. It costs $20, but is free if you are switching to certain services, including Yahoo or Comcast.

One caveat: My test of TrueSwitch occurred five years ago, and, while it worked well then, I can’t be certain that it still does.

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

I advise this delay because the Windows world is on the verge of an upheaval. Microsoft is about to replace its tired, insecure Windows XP operating system with the first all-new version of Windows in more than five years. It’s called Windows Vista, and it’s likely to be more secure and easier to use. But Vista won’t be available until around Jan. 30, 2007. So, all those brand-new Windows computers you might buy this holiday season will be powered by an operating system that is on its deathbed.

Of course, you can upgrade most new Windows XP computers you buy now to Windows Vista after January. And starting today, Microsoft and PC makers are offering an Express Upgrade program that will provide copies of Vista for free, or at reduced prices, to people who buy Windows XP machines bearing a “Vista Capable” sticker from now through mid-March.

The catch is that upgrading PCs to major new operating system releases can be a tricky business. Often, it works just fine, but in many cases there are significant problems. It’s always better to buy a new PC that has been matched at the factory with the latest operating system. Waiting just another 90 days could save you a lot of upgrading aggravation.

Also, the free or discounted upgrade program will, in most cases, entitle users of the common Home edition of Windows XP to obtain only a stripped-down version of Vista called Home Basic. That version lacks many of the coolest features of the Vista user interface.

What if you want an Apple Macintosh instead? Should you wait? After all, Apple is also planning an all-new version of its operating system, to be called Leopard, in 2007. I don’t advise Mac shoppers to wait, for several reasons. First, Leopard isn’t due until spring of 2007, months after Vista. Second, Leopard won’t be as disruptive an upgrade as Vista because it is the fifth major revision of Apple’s operating system since 2001, not the first. Third, because Apple makes both the hardware and software, Mac operating system upgrades tend to be relatively easy.

Apple isn’t offering holiday buyers any discounts or free upgrades to Leopard, but the company says all of its Mac models currently being sold will work fine with the new system. The current Mac operating system, called Tiger, already contains most of the key features promised for Windows Vista. I still regard the Apple iMac as the best consumer desktop computer on the market.

But, if you want a Windows desktop or laptop and you can’t wait until February for a model that is preloaded with Vista, here are some guidelines. As always, these tips are for typical mainstream users, not hard-core gamers or people doing intensive video production.

Vista compatibility: Make sure your new PC has a sticker that says “Vista Capable.” But this sticker guarantees that it will work with only the stripped-down Home Basic version of Vista. If you want to be able to upgrade to the Home Premium version of Vista, which has the full user interface and other features, or to several other versions of Vista, look for a computer designated “Premium Ready.” Naturally, these latter machines will cost more.

Memory: Microsoft suggests 512 megabytes of memory, or RAM, for the stripped-down Vista Home Basic, and 1 gigabyte of memory for full Vista. But I strongly suggest doubling those amounts. If you want to run Vista with all its features, get 2 gigabytes of memory.

Video: Vista Home Basic can run on any graphics hardware that can support a Microsoft technology called DirectX 9. This includes many “integrated” graphics systems, which don’t use a separate video card.

Vista Home Premium and other versions will work best with a separate, or “discrete,” graphics card that has at least 128 megabytes of dedicated video memory. Microsoft says even integrated graphics systems, like Intel’s chip sets labeled 945 or higher, will also work, as long as the computers containing them are labeled “Premium Ready.”

Processor: For stripped-down Vista, a processor running at 800 megahertz or faster should be sufficient, according to Microsoft. For full Vista, the speed rises to 1 gigahertz. For anything other than stripped-down Vista, I’d strongly suggest buying a so-called dual core processor, like Intel’s Core Duo or Core 2 Duo, which pack the equivalent of two chips into one.

Hard disk: Disk storage is already copious enough for Vista, and buying large amounts is inexpensive. For stripped-down Vista, I’d go for at least 60 gigabytes of hard-disk space. For full Vista, I’d boost that to 200 gigabytes, to accommodate lots of music and video.

Price: Don’t spend extra for a slightly faster processor. Invest in more memory instead. And factor in the cost of Vista. Even the Express Upgrade program may pay only part of the cost of an upgrade, which ranges from $99 to $259, depending on the version of Vista you want.

So, wait, if you can. But, if you must buy now, don’t scrimp on the specs.

• Email me at mossberg@wsj.com.

Now, there’s an even better approach to running Windows on a Mac. It’s called Parallels Desktop for Mac, and it’s from a small Herndon, Va., company called Parallels. It emerges from testing today and goes on sale for $79 at the company’s Web site, parallels.com.

I’ve been testing Parallels Desktop on a new MacBook Pro laptop, and have found it works very well, despite a few drawbacks. I prefer it to Apple’s solution, even though the Apple approach is free and also works very well.

Apple’s system, called Boot Camp, has one big limitation: It allows you to run only one of the two operating systems at a time, requiring you to reboot the computer to switch between them. As a result, you can’t quickly jump between Mac programs and Windows programs. You can’t, for instance, simultaneously download your corporate email in Outlook using Windows while editing a home video in iMovie using the Mac OS.

With Parallels Desktop for Mac, you can do this. You can run any combination of Mac and Windows programs at the same time, on the same screen. No rebooting is necessary. You can even cut and paste material between Mac and Windows programs, and share files between the two environments.

The Parallels approach, called virtualization, runs Windows, with all its features, inside a window in the Mac operating system. It creates a faux Windows PC, called a “virtual machine,” that co-exists with Mac OS X. You can devote the full screen to either operating system or you can reduce Windows, and whatever programs it’s running, to a window on the Mac that can be dragged anywhere on the screen and made as small or as large as you like.

Unlike Boot Camp, Parallels Desktop can run every version of Windows back to Windows 3.1, not just Windows XP. It can also run Linux and even older operating systems like OS/2 and MS-DOS. You can even create and run multiple virtual machines, with different operating systems inside, up to the limit of your Mac’s memory.

Virtualization isn’t a new concept, and it’s not even new on the Mac. Microsoft offers a product called Virtual PC for Mac that runs Windows inside a window on older, pre-Intel Macs. But Virtual PC runs painfully slowly on these older Macs, and it can’t run every Windows program. It doesn’t run at all on the new Intel-based Macs.

Parallels Desktop runs Windows a little more slowly than Apple’s Boot Camp does because it is accessing the Mac’s hardware through the Mac operating system rather than directly, as in a dual-boot system. But, in my tests, it was very snappy, as fast as many regular Windows computers.

Inside my virtual Windows machine, I was able to run programs like the Windows version of Microsoft Office, the Windows versions of the Firefox Web browser, iTunes, Adobe Reader, Google Earth and more. All worked well, as did Microsoft’s Internet Explorer Web browser, Google’s Picasa photo program and Google’s Google Talk instant-messaging software.

I was able to do email in Apple’s Mail program while simultaneously watching a baseball game in Internet Explorer inside my Parallels Desktop Windows virtual machine. I wrote part of this column in the Windows version of Microsoft Word and part in the Mac version, cutting and pasting between the two.

And, unlike Boot Camp, Parallels Desktop doesn’t require you to dedicate a fixed section, or “partition,” of your hard disk to Windows. Its virtual Windows computer is contained in a big Mac data file that uses only as much space as Windows needs.

Setting up Parallels Desktop is fast and easy, though some novice users may find the program’s terminology a little daunting. As with Boot Camp, you have to supply your own copy of Windows to install once you create the virtual machine. And because the virtual Windows machine created by Parallels behaves like a real Windows computer, you have to install the usual raft of Windows security software.

So what are the drawbacks? I couldn’t eject a CD in Parallels without switching back to the Mac environment. Parallels treats fast USB 2.0 ports on the Mac as if they were slower USB 1.1 ports. It doesn’t support Microsoft’s DirectX technology, which many games rely on. The company pledges to fix these things in future versions.

Also, if you elect to use the optional file-sharing feature, your Mac data files could be corrupted or erased by a Windows virus. For that reason, this feature is turned off by default.

Still, Parallels Desktop is a very good product and a pleasure to use. It’s like having two computers in one, the best of both worlds.

• Email me at mossberg@wsj.com.