Phenom x6 + 6 gigs of ram and overclock it to 4.0+. Cheap, viable solution that should be around $1,000 tops with a fast SSD + storage HDD and a decent video card. I'm not sure which video cards support 3DSM rendering - you should google that. If any of them do - invest heavily in a good GPU setup and drop the CPU down to an i5 750 or a 955. That would be my path anyway.