If I ain't mistaken, he has a Core 2 Duo E8400, ATI HD4850, 4GB RAM & this is hooked up to a Sony HDTV. Max resolution being 1368 x 768 (unless he has changed his monitor).
Anyway if the last game you finished was Dark Sector, I assume you haven't touched much since end of March, as that's the time when DS came out.
Here's some games released post DS:
The Wheelman
Wanted: Weapons of Fate
The Godfather II (you can skip this one)
The Chronicles of Riddick: Assault on Dark Athena
Braid
Velvet Assassin
X-Men Origins: Wolverine (assume you have already played this)
Terminator Salvation
Damnation (avoid it like plague)
Prototype (get it ASAP)
Ghostbusters: The Video Game
Transformers: Revenge of the Fallen
A few oldies which you might have completed:
F.E.A.R. 2: Project Origin
NecroVision
Cryostasis: Sleep of Reason