Can you post your system specs? Anyway, assuming you have a decent build, here's some good games kinda like CS:
Unreal Tournament 2k4
Halo PC
Doom 3 and/or Quake 4
Half Life 2
FEAR (if your PC can handle it)
Call of Duty 2
I'd also recommend the Grand Theft Auto series, which aren't really like CS, but are a lot of fun.