A good 650 watt PSU will power almost any home style PC using any CPU and any video card with a single GPU. PC's take surprising little power until you start using multiple GPU's.
One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 (same power requirements as a GTX460 or a 6870), a Gigabyte EP45-UD3P motherboard, 3 hard drives (2.6 TB total) and an optical, and a Soundblaster card all powered by a Corsair 750TX.
Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% efficiency, the system pulls 300 watts from the PSU.
The 650 watt Antec that you are considering will have plenty of power for even something like a GTX580.