nice clocks there for that card... the 6600GT is about 500/1000 std and it's not expensive, around $120 USD, which is great value for price... even the 6800GS's price is going down too... not to say the 7800GT between $400 and $500, but that's overkill for now
I tried Quake 4 on the 6600GT 128Mb and runs fine at 1024 x 768 on max settings in multiplayer. F.E.A.R. still thinks it needs 256Mb to get full textures, but it runs fine at same resolution.
Btw, NFSMW runs excellent at 1280 x 1024 at max settings.