yes that 1gb is a great price and given that AMD has been developing the phenom alongside it i think the future proofing could be very good. Especially.... when you consider its potential in crossfire!!!
Anyway about PSU'S for this..I found this review that claims the 600w gamexstream should handle this card.
The review does seem a bit optimistic as they ran two 8800GTXs and ocd an extreme cpu with endless hardrives and fans.
Legion Hardware
Hopefully when i get the 2900XT it wont blow my system

I wont be overclocking it till i do the spring update and it will just get the two 6pin pci express connections.
b1lk1 let us know how it handles on your system when you get it