Should eat up all games on highest settings.
Just to note, if you intend installing a 32 bit OS you won't benefit from the full 4 GB RAM. Might be better if that's the case to just buy 2GB but with faster timings than CL5.
Also my MOBO Asus P5N32 sli premium, doesn't like all 4 memory slots being full, and I can't sort out this issue,even with latest BIOS.
My setup Core2Duo 6600, 2GB PC6400, Nvidia 8800GTS flies through the likes of Crysis, Bioshock, COD4 et al, but if money isn't an object, go for iy. #;-)