Ultimas: 7, 7/2, Underworld, Underworld II, Online
Fallout 1 & 2
Dunno if Planescape: Torment would run on that, if so DO IT
Grim Fandango (as previously suggested)
...
There was a really strange, but cool, game named "Dark Seed" made based on HP Lovecraft's work that should run on that
Lords of the Realm II
Heroes of Might and Magic III (I think)... if not then go with II (better soundtrack anyway)
The old Bladerunner game was pretty sweet...
If nothing else, PLEASE check Ultima Underworld II, Planescape: Torment and Fallout (if you like RPGs, at least).