Why are you guys spamming out sollutions, when the guy hasn't even described the problem properly? ;-)
Seriously, though, Windows XP x64 is rock solid (it should be, it's based on Windows 2003 server), and most, if not all 32-bit applications run fine. It can be hard to find drivers sometimes, but it's generally not a problem for anyone with a strong Google-fu.
When it comes to performance, I find a well-tweaked Windows XP install to be somewhat faster than the common Linux distributions' (Ubuntu, Mandriva, etc.) standard installations. I wouldn't compare a fully tweaked Linux system to a fully tweaked XP system, as those distros usually are designed for a specific purpose.
Nothing beats puppy on a stick, though! ^^