After more than 18 months of delays, the shipping version of Microsoft's Windows XP Professional X64 Edition operating system is finally here. But even if your PC has a 64-bit CPU, we advise waiting for Longhorn, Microsoft's next-generation Windows due out in 2006, unless you work with data-intensive programs such as video rendering, 3D animation, or CAD and engineering.
XP X64 can process data in 64-bit chunks and address a whopping 128GB of RAM (up from 4GB in today's systems), allowing a dramatic increase in performance by keeping most of the data an app might need in RAM rather than on the slower hard disk. It looks and acts much like the 32-bit version of XP, and these days more popular software either comes in a 64-bit version or works with the new OS. (For details on its features, see March's "XP Goes to 64 Bits"). Caveats abound, however: Compatibility with existing hardware remains one trouble spot, and--more alarmingly--Microsoft says that installing the new OS will void your PC's warranty. Vendor policies vary on this, so check with your PC's maker before you upgrade.
