Originally Posted by Roxter
Corsair 620HX or FSP Fortron FX760E 760W
The Fortron is $99 on sale and the 620HX is $139.
I would normally get the Fortron but I may get a 2900XT.
When considering PSU choices, it's best to not look at the wattage rating, as these can sometimes be inflated. Look instead at the amperage produced on the different wattage rails (specifically the 12V rail(s)), especially since you're basing your decision on a particular video card's demands.
Having said that, I've got the Corsair HX620W. Excellent power supply, and it was one of the top-rated PSUs evaluated recently by Computer Power User magazine.
Fortrons are usually fine as well; Fortron is one the largest PSU manufacturers in the consumer sector, so they've got a solid reputation. They also are sub-contracted to manufacture PSUs for other companies.
Anyway, look up the amps required by the 2900XT. That ought to be your guide to your decision.
Hope this helps!