GTA, TrackMania, NFS, Juiced 2, Forza 3.
Track simulation lol? I have used to play it a lot on my older machine, but idr any good titles.
Sports maybe? I play FIFA\PES all year long.
Starcraft 2, Diablo 2, Dragon Age?
Go to some decent torrent website and look up games, not advising to download from there, but it will give you wider specter of available games. After you can look them up on youtube (IGN, gamespot has nice video reviews which will help a lot).