Dhoom 3
Pop: Sand of time (may have some problem with the shader version but i played it quite well on my machine)
Prince of Persia: Warrior Within
Prince of Persia: The two throwns.
NFS series. i am playing NFS: Pro street these days at lowest settings but It runs quite well.
Freedom Fighter
Age of Empire III & II, Age of mythology, Rise of Nations.
Call of Duty 1 and Call of Duty 2.
medal of honour: Alied Assault
Medal of honour: Pacific Assault
If you have good onboard Graphics and ram. you can play most of the games.
I too have onboard Graphics of 256 mb and shader model 2. so shader model 3 games are away from me. But I am planning to buy a HD 4850 soon.