Many Windows users have never upgraded from XP to Vista, and likely never will. (I’m in that group – I may upgrade to Windows 7 at some point, but I won’t go to Vista.) XP is good enough for my purposes and is likely to remain so for a while.
If you’re of like mind, PC World has put together a slide show that has tips on how you can keep your Windows XP up-to-date so that you don’t need to upgrade. Many of the features in Vista and Windows 7 are available as separate downloads or as equivalent third-party applications. For example, you can install Windows Defender, Google Desktop, and TweakWindow. And even if you don’t want to add anything more, there are system maintenance tasks like disk defragmentation and registry cleanup that will keep your system running smoothly for a long time.