I have good performance with GTX 570 too. I think CPU is not important for this game, GPU is the most important.

Yes, I'm hoping they get SLI/Xfire support going soon. As far as I figure it there is no single-card solution that can play the game adequately at high settings, as it stands. Plan is to get two unlocked 6950s and go to town, so to speak (I am curious how they'll handle London).

So the Xfire/SLI support should probably be a fairly big priority, behind the general optimizations.