Im going with an Ultra X-Finity 600-Watt ATX Dual 80mm Fan SATA-Ready SLI Ready. Just google Ultra X-finity 600w review. The only down side to it is the efficency is a little low. Which causes more heat. That might be an issue for you since your using a AMD.
I'm buying a new gaming rig this week and need a good PSU to power this thing. Here are the specs:
Athlon X2 3800+
eVGA 7900 GT KO
MSI K9N SLI Platinum AM2
Corsair Dual channel DDR2 800mhz TWINX C4 2x1024
Seagate 250GB SATA-300
NEC DVD burner
I was looking at Ultra PSUs but read somewhere to stay away from those, I don't know much about PSUs so I have no idea which one to chose now.
Edit: I forgot to say that I might go SLI this winter.
Top PS makers include PC Power and Cooling, FSP, OCZ, mushkin, Sea Sonic, Tagan and Hiper. You'll find many people that use and love Antecs and it's easy to see why because of performance per $ but I got burned twice by them and just can't recommend them. Chances are, you could get a mid-range unit and be happy with it, but if it dies and takes out your pricey components, just remember that I warned you...
WRT running SLI, you can look on nvidia's site for a list of approved units, but if you run current-rich GPUs, some on the list will not handle the load. I would not build a single GPU box with less than 26A of +12V and would want around 40A or more for an SLI machine. Realize that two OC'ed 7900GTs plus an OC'ed CPU could even stress a 40A power supply, especially if your case temps are high.