check out this list...
it hasn't been updated for some time, but there's a fair few games there.
by the way, i have grid (steam version) working fine without having to fiddle about at all.
dirt 2 is a very good racing game, made by the people who wrote grid, but is newer, better graphics and more off-roady, as the name suggests.
there are also loads of good shooters, such as cod modern warfare 2, battlefield bad company 2, bioshock2, borderlands, left4dead 1+2...
it's always a good idea to quickly check a game's website and/or forum before you buy to make sure of compatability, but these days it would be very odd indeed if a new game did not work with windows 7.
it's also a good idea to install games outside of the program files or program files (x86) folders, as UAC can sometimes cause problems.