I would go with a new power supply, as well as the semi expensive 5770. Its about $160ish, and should be able to hybrid crossfire with that 785g chipset just fine.
As for the nvidia fanboys, the fermi still has minor flaws and until nvidia fixes their sh*t, I would wait.
With a new PSU, and a 5770 running in Hybrid Xfire (crossfire), you would have no problems whatsoever. As for your CPU, if you wanted to upgrade, you could get the phenom 2 tricore, it is better than the quad core you have. However the one you have is good enough to run just about any game on the market at medium to high settings.
Btw what is your exact mobo? I can not for the life of me find your motherboard anywhere.
What kind of ram do you have? How much and what kind? ddr2 ddr3 1066 1333 1666?
Edited, Sep 23rd 2010 11:29pm by lightningcount
Lost and Crazy