With the advent of Windows Vista, we've decided to put our operating system section on a separate page. Microsoft's new operating system comes in an even greater number of flavors than Windows XP, and we couldn't really explain all those choices in a handful of paragraphs.

Before we begin, some of you may be wondering whether Vista is really worth it in the first place. After all, Windows XP still works, and from a distance, Vista looks like little more than a prettied-up version of the same old operating system. Appearances can be deceiving, however, and Windows Vista is really far more than Windows XP with a new user interface.

For one, Microsoft has completely overhauled the OS's kernel with an emphasis on security, stability, power management, and performance. Because of those changes, Vista makes it much more difficult for malicious software or poorly-crafted drivers to wreak havoc on the operating system. Vista's built-in Windows Defender application and User Account Control mechanism both work to prevent malware and spyware infections. (Although we've found UAC to be a little annoying in practice, the extra hassle may be worth the peace of mind given the severity of the spyware/malware phenomenon.) Also, most device drivers no longer run at the kernel level, so if they crash, the effects should be no worse than if any random application were to take a dive.

Along with superior stability and security, Vista boasts system-wide instant search, a new networking stack, a new audio architecture with per-application volume control, and DirectX 10. If you want to take full advantage of a shiny new GeForce 8800 graphics card in upcoming DX10 games like Crytek's Crysis, then you'll want Vista. Really, the folks at Microsoft haven't been sitting around twiddling their thumbs in the five years since Windows XP's release, and if you're building a new PC now, Vista looks like the way to go.

Which edition?
So if Vista is the right OS, which version should you get? To make things simple, here's a chart that lists the four retail Vista editions and the major features they include for desktop systems:

As you can see, Windows Vista Home Basic is stripped to the bone and doesn't come with any of the goodies the more expensive editions offer. Since it costs just $40 less than Vista Home Premium, we think it's a pretty poor deal. Besides, this edition lacks the Aero graphical user interface, and Vista just isn't Vista without shiny transparent windows and live thumbnails.

With the pricier Home Premium version of Vista, Microsoft has essentially produced a successor to Windows XP Media Center Edition 2005 that's intended to be more of a jack-of-all-trades for home desktops than an OS aimed squarely at home theater PCs. Home Premium includes Microsoft's Windows Media Center software, which rolls PVR and media playback functionality into an attractive GUI optimized for display on a television. That media-centric functionality is bolstered by Windows Media Extender, which allows you to access movies and music stored on your PC via compatible Media Center Extenders like set-top boxes and even the Xbox 360. You also get backup scheduling tools, as well as software to burn your own DVDs and make high-definition movies. This version of Vista would get our vote if it weren't for the lack of Remote Desktop Connection (RDC) software.

RDC allows you to connect to your home PC remotely, and it's not included in Vista Home Premium. Several of TR's editors use RDC extensively in order to control their main PCs from their laptop computers. Thanks to RDC, there's no need to install every last program on a mobile computer or to sync all data between one's desktop and laptop systems. This is a great option, whether on the road or from the couch, so it's not a capability we'd write off lightly.

Your least expensive option with RDC support is Vista Business. As its name implies, this version of Vista is designed mainly for professional users. Vista Business lacks media center functionality, but makes up for it with industrial-strength backup and networking tools. If you couldn't care less about turning your PC into an entertainment center, coughing up the extra $60 for Windows Vista Business is probably your best bet.

Last, but certainly not least, there's Vista Ultimate. Fragmented features sets may save you some cash, but there are some who just want it all. This edition contains all the features from the Home Premium and Business versions plus BitLocker, a real-time hard drive encryption tool that helps keep your data safe from prying eyes. Unless you really need everything in one package or regularly blow your nose with $100 bills, though, the cheaper Home Premium and Business editions are probably more sensible choices.

32-bit or 64-bit?
The x64 version of Windows XP was somewhat of a dead end because of limited third-party support, but all retail editions of Windows Vista offer both 32-bit and 64-bit binaries in the same package. (You'll probably need to hit Microsoft's website and cough up a $10 fee to get the actual 64-bit installation disc, though.) You therefore have the option of installing whichever version you please, and most companies releasing Vista drivers have done so in both 32-bit and 64-bit flavors. Since all of the processors we recommend in this guide are 64-bit capable, the 64-bit version of Windows Vista seems like a pretty compelling choice. (For some background on what makes 64-bit computing different at a hardware level, have a look at our take on the subject.)

Vista x64 also offers some security features the 32-bit version lacks. According to this article by Paul Thurrott, Vista x64 will "virtually eliminate" remote system attacks, prevent malicious software from patching the operating system kernel, and support the security features inside AMD's and Intel's latest processors at the hardware level. And of course, having a 64-bit operating system means you can use more than 4GB of system memory without any convoluted workarounds.

There are a couple of caveats, though.

For one, Vista x64 presents some device driver challenges. Older 32-bit drivers won't work on this OS, so your hardware will either need to be supported by Vista's built-in set of drivers or the device manufacturer will have to offer 64-bit Vista drivers. Most of the core system components we've recommended already have 64-bit Vista drivers, but if you're carrying over peripherals like printers and scanners, you'll want to look into drivers for them. Also, Vista x64 requires all drivers to be signed. Since bad drivers are frequently the culprit in an unstable system, this requirement makes sense in environments where stability is crucial. It's not so great, though, if you're the type to run user-customized graphics drivers or the like.

Also, the x64 edition of Vista breaks compatibility with older applications in a couple of ways. Vista x64 can't run 16-bit software, which will matter to those folks who are attached to a really old application for some reason. Also, Thurrott points out that 64-bit versions of Vista lack automatic registry and file redirection, a key element of Vista's backward-compatibility provisions. As a result, more recent 32-bit and even 64-bit applications written for Windows XP may not run properly under Vista x64.

We're not quite sure where PC enthusiasts will go on this issue. There may be something of a split between the gaming-oriented enthusiasts who pick the 32-bit version of Vista for minimum hassle and the computer propellerheads who go the x64 route for maximum performance and security. As for us, we're tentatively recommending the x64 version of Vista here, since our system guide is oriented toward those building themselves brand-new PCs. By and large, the newer hardware recommended here ought to have 64-bit drivers ready, and the x64 version's improvements in memory support, security and the like are probably worth the hassle, so long as you can successfully navigate the hardware and app-level incompatibilities. With a retail version of Vista, nothing should stop you from giving Vista x64 a go and reformatting and installing the 32-bit version if you run into problems.

OEM or retail?
Just like Windows XP, Vista is offered in both OEM and retail versions. The retail versions are intended for consumers, while the OEM versions are officially intended for use by PC system builders. You can get a nice discount by going with an OEM version of Windows, but you'll be making some compromises in the process.

For one, the retail versions of Vista ship with both 32-bit (x86) and 64-bit (x64) edition DVDs in the box, but the OEM versions require one to choose up front, because they come with only one of the two.

Additionally, Microsoft has stated that its licensing terms won't stop enthusiasts who run retail versions of Windows Vista from changing major hardware components regularly or from transferring the OS installation to another PC. However, OEM versions are technically tied to the first systems on which they're installed, and Microsoft may choose to enforce that limitation via its software activation scheme at any time. If all of this sounds confusing to you, that's because it is. For more on Vista OEM and upgrade licensing issues, see our article on the subject. The bottom line here is that you're taking a risk when buying an OEM version of Vista, and it may come back to bite you if Microsoft invalidates your software license after a hardware upgrade. If you're likely to upgrade your PC before Microsoft releases the next version of Windows, you should probably get a retail copy of Vista. Then again, we don't yet know how strictly Microsoft will enforce the OEM transfer limits. The gamble could pay off.

If you do choose to gamble on the OEM version of Vista, you will be saving some money up front. Here's how the OEM and retail pricing compare.

We aren't keen on paying Microsoft's retail prices when OEM versions are this much more affordable, but we dislike the limitations that the OEM versions of Vista impose, so our nod goes provisionally to retail. If you've already decided the 32-bit versus 64-bit question and you're willing to risk it, though, the OEM discount might be worth taking.