HairyFish

A friend of mine has a 2 GHz P4, 512 MB RAM and a GeForce 6600GT. These meet the minimum spec for the game apart from the processor. Is this likely to make a big difference? I've heard that GPU performance is far more important than CPU performance these days. Is the game likely to be playable on his system? (If no-one knows for sure, could someone test this by underclocking their CPU or something?)