What is a suitable power supply for a 2x ATI Cards in Crossfire Configuration?

"if you're running crossfire on a 57xx series, the GPU's are quite low power (in comparison to 48xx series and nvidia GPU's)

so corsair's value range should be fine (VX series if they do them in the required power range), antec, Enermax and OCZ all make decent PSU's too

this article page has a power consumption chart for ati crossfire cards.

as has been said, go for an 80+ certified and you should be fine (most efficient at 80% of maximum load)"