+2 on HD5770. GTX200's are obsolete/discontinued and I believe that's why the price is going up on these becuase there arn't that many left in the market. I just built my housemates pc with hd5770 and it runs BFBC2 on 1080p resolution cranked up all the way perfectly. granted he has i5 but you're cpu should be fine as well.
As for the PSU, since your mobo can't CF/SLI i'd think ~650 should be good. I recommend Corsair. I believe they have a 650W unit for $90'ish. I used Antec earthwatts 650 on my friend's pc and it runs well and it's cheaper.