You can buy a cheaper PSU and invest the difference in a better CPU and 8800GT with 512MB(it is 10%-20% fasterr than the 256MB version).
I am running P35-DS4, E6420 @3.5GHz (7x500) 1.35v, 4x1GB DDR2 @1000 CL4 5-5-16 2v, 2x250GB + 400GB HDD, 2xDVD-RW, Creative Audigy2, TV/FM Tuner, 8800GT...