A 650W PSU is more than good enough to run the 560Ti. I believe the minimum recommended PSU is 500W. I run my 560 Ti fine on a 600W PSU.
Assuming you don't want to break the bank, an i5 is the way to go. You don't want to have to get stuck upgrading the CPU or the motherboard a few months after you build your PC. The i5 2500K is just as good as any of the i7 models also.
The i3/i5/i7 are all Sandy bridge CPU's. Intel is releasing Ivy Bridge in a few months, but they will be pricey. Also from what I've read up on the i5 2500K and the good i7 CPU's beat out any of the AMD equivalent CPU's.