I have a 512MB RAM card and a 256MB graphics card and all the games that I have tried to play work fine for me! Those are very basic specs but thery do the trick!

I think you need a decent video card to play any good game at least a 256 mb video card you can get away with 128mb card but its not as good I would also suggest 1 gig of ram I have 1.5 gigs of ram