Get any nvidia or ati card. It really doesn't matter whatsoever (just not a matrox or intel onboard or something like that)... unless you are using vista then your desktop is rendered by the cpu and is just passing through the card. The card really only does work when you run 3d games.
Oh, and movies are ALSO all rendered by the CPU... unless you have a specific card and are using one of a handful of programs to play it.