I dual boot vista and XP, and its been my personal experience, Vista runs faster on everything from games to internet to video, Ive had not a single compatability issue with it, I have with XP, Xp is ok with plug and play, but vista dominates, if the drivers arent on it, it finds them and downloads them without even asking me.
I still like XP but I do feel vista is to XP what XP was to 98, a good upgrade.