I have almost the same specs.. Quad Core CPU Q6600@2.4ghz, 2Gb RAM, WinXP SP3 32-bit and GT 430 1Gb..
I'm already used to freezes/stuttering when action starts.. unfortunately I unable now to improve the specs of my PC..
I think all you need are a bit more RAM (4-6 Gb) and Win7 64-bit.. maybe new video card as Webster noted..
