About the only need for XP would be if you ran certain programs, like the most recent version of Adobe After Effects (Xp only), or others of the latest. I still have my Win2k and drivers and Service packs all preserved, and if needful, will go back to that as my main OS and use XP and XP64 solely for graphics work....and yank out every service I don't truly need for that purpose. Right now the only true reason to upgrade to Vista is if you are a gamer, and want to play one of the forthcoming DX-10 games...once they are actually released.