No option for Mac OS X or Linux? Of the 2, XP is the better OS in all respects, vista runs like total shit on my AMD X2 3800+@3Ghz w/ 2Gb of DDR2 800 @ 4-4-4-12 and nvidia 8600GTS OC.
But seriously, for everything non gaming A Mac or
Ubuntu Studio based comp is far better, I use
Ubuntu Studio based on the currentlt release of ubuntu 7.10 on the pc and I run OS X 10.4 on my dual 1Ghz G4.
Gaming isn't too bad on linux right now, I've got Enemy Territory: Quake Wars, Never winter Nights, Regnum Online, Quake 4, Doom 3, X2 all running natively and will soon have Unreal Tournament 3 going as well. Other games Like World Of Warcraft and Guild Wars run fine in linux as well tho you'll need to use Wine, Cedega or Crossover to play them.
Best thing, Mac OS and Linux don't get internet herpese from going to the internet whore houses lol.