I suggest not using Vista. It is constructed to severely decrease quality of sound, graphics and processor speed if you do something the computer doesn't like. Say, play a pirated game or a game not in a databank somewhere.
Lol, you're paranoid. If a game's quality decreases, that's solely the fault of the game. I run many ... otherwise
acquired games on Vista with no hassles. Stuff like CS:S, KOTOR, Halo, HL2 - they all run just fine. Office '07 too, if you're curious.
The only place a "databank" factors into it is when a game registers in your Games folder - Vista will look up game info via Microsoft, but believe me, it doesn't do anything malicious against copied games.