dont get the 5450's the wireless rear channel suffers from static and poor sound quality. Go for the tried and true z-5500's
As for the hard drives, Grab 2 74gig raptors, and 2 750gig Seagate Barracuda drives
I dont think he'd even need a 1kw psu for that system, seeing as the Conroe uses the new 65nm resulting in lower voltage requirements and thus lower heat output. Not sure on the g80 but it probably will be sometihng along the same lines. Seeing the way gpu hsf's are getting so much smaller all the time. i.e. Asus 6800gt tdk to the 7950gt heatsinks