Re: New PSU and GPU recommendations
You won't see any downgrade, loss performance or anything with a PCI-e 1.0 slot.
Your sydstem will easily run on a 500ish Watt psu.
As for a psu, I always say, for this level of psu, start at a 85-90 dollar range before rebates. Look for at least a bronze rating, means 80% for 20-85% loaded. Better color better rating, but more costly.
Look for brands like Corsair, SeaSonic, Silverstone, OCZ, Antec. These are the good reliable brands.
However, though I said 500, I'd look more at 6-650 as psus can last a few upgrades, so might as well get a bit larger size now so it can last longer... Interms of upgrades. If you ever think of sli/xfire, though your board doesn't support it, I'd go to a 700 due to the 4 pci-e plugs usually needed now, weith newer cards.
Foldie = i7 950@ 4.0Ghz Gigabyte x58a-ud3r EVGA 970 SC Corsair H100 Corsair hx520 3x2gb OCZ Gold Corsair 650D
Woohoo = L5639 @3.1Ghz EVGA SR-2 gtx 260-216 Hyper 212+ Corsair 1050hx 6x2gb Corsair XMS3 Blackhawk Ulra
Alienware 18 - SLI 770M 4700mq 16Gig