Don't use one of the first gen Phenom, they really aren't very good. The 720 BE would be a much better processor.
The CM Real Power Pro series are ok, but better for the money would be a Corsair 550vx.
Seagate drives are problematic, go with a WD 320 or 640gb, they will be faster.
I would also go with a 4870 instead, or a GTX 260