It's not often that I can easily point to the question I'm most often asked, but these days it's simple: Readers are thinking of buying a new PC and want to ensure that it's powerful enough to run Windows Vista, Microsoft's upcoming OS. Because Microsoft hasn't yet revealed Vista's exact system requirements, customers are afraid that they're going to be somehow locked out of the upgrade if they get the wrong system. A related question, of course, is whether these customers should wait for Vista before upgrading.

That last question is the easiest one to answer. If you need a new PC now, you shouldn't wait. On the flip side, remember that any PC purchase is out of date almost the minute you get it home, because PCs are updated so frequently these days. For example, suppose you just purchased an expensive new Pentium M-based laptop. I've got bad news for you: Intel is now shipping the Core Duo processor, which will replace the Pentium M in the marketplace. Or perhaps you're the proud owner of a new Intel Pentium D-based desktop PC. More bad news: AMD's dual-core chips are more powerful. You know the drill.

As for Vista, here's what we know. Microsoft says, vaguely, that Vista will run on any system that includes a dedicated, DirectX 9-compatible 3D graphics card. Beyond that, Microsoft isn't saying much. However, thanks to my insider contacts and some Microsoft internal documentation, I can tell you exactly what you need to get the best Vista experience. The good news is that you don't have to wait. It's all available right now.

Microprocessor
If you're buying a desktop computer, Vista will work just fine with a 3GHz Pentium 4 processor with HyperThreading, but these days you can't even find such a system. Intel's successor to the Pentium 4, the dual-core Pentium D, is even more powerful, and AMD's dual-core designs are the best yet. Any mainstream microprocessor will form the basis for a great Vista system, so you have no worries there.

Another thing to consider on the desktop side is the x64 processor extensions, which add 64-bit capabilities to the chip and let you run one of Vista's 64-bit versions. I do recommend x64-compatible chips, but those who upgrade to Vista in the next year or so will likely want to stick with the 32-bit Vista versions for the short term. However, going x64 today will ensure that you have the ability to upgrade to an x64 Vista version in the future. All of AMD's mainstream desktop microprocessors are x64-compatible today, as is the Intel Pentium D and certain Pentium 4 versions.

On the notebook side, Microsoft recommends a 1.86GHz Pentium M processor 750 or higher, or an AMD Turion 64 Mobile Technology, Mobile Sempron, or Mobile Athlon 64 processor. Intel has recently switched over to the Core line of processors, so I'd recommend that. The Core Duo features dual-processor cores and will give you the best performance. That said, only AMD offers an x64-compatible mobile processor right now.

RAM
Microsoft says that Vista will run acceptably with 512MB of RAM, but that's a low-ball figure. My personal recommendation is to go with 1GB of RAM or more. Understand that Vista, like all Windows versions, is a RAM hog: It will utilize whatever you throw at it, to the physical limits of the system. Those limits are 4GB for 32-bit systems and 128GB for x64.

Graphics
As noted above, Microsoft says a DirectX 9-compatible 3D video card is necessary to use Vista's gorgeous Aero UI. (Otherwise, you'll see a bland Windows XP-like interface.) However, it's not that simple.

First, most integrated graphics chips (common on notebooks) aren't capable of displaying Aero, although Microsoft is working on making Intel's very latest integrated graphics chipset (available on some Core Duo systems) work with Aero.

The amount of dedicated graphics memory is also important. Although a 64MB graphics card is adequate for a 1024 x 768 display, you'll need 128MB or more for higher resolutions. My recommendation is to get a graphics card—whether it's for a desktop or notebook—that includes at least 256MB of RAM.

Display
Early in Vista's development, Microsoft was touting widescreen displays and noted that Vista would run best on such a system. Although I do believe that widescreen displays offer huge advantages over standard 4:3 aspect-ratio displays, Vista is no longer being architected to work best on such a display. So, virtually any monitor should work, as long as it's capable of 1024 x 768 or better resolution. That said, you'll still be more productive with a widescreen display, and certain Vista features, such as the new Sidebar, actually do work best on a wide screen.

Hard Disk and Storage
Today's PCs—both desktops and notebooks—typically utilized Serial ATA (SATA) hard disks and IDE-type optical drives, and this scenario won't likely change for the foreseeable future, although optical drives should slowly move to SATA as well. As with most system components, faster is always better. Therefore, you should shoot for a 10,000rpm drive on a desktop or a 5400rpm or 7200rpm hard disk on a notebook. With an optical drive, less is more: Get a single rewriteable DVD drive that can read and write to every available optical disk format.

Why Upgrade?
Even when Vista ships later this year, you probably won't want to upgrade. First, Vista will run more slowly than XP does, and it will be less compatible with your hardware and software. Also, you might find some of the changes in Vista jarring. My advice is to hold off on Vista until at least mid-2007. By that time, most of the initial bugs and incompatibilities will have been worked out, and software and hardware makers will finally be directly supporting the new system in droves. That said, I know this advice won't be particularly well heeded: You guys want to upgrade, and you want to do so as soon as possible. Hopefully, this guide gives you all the information you need.