GTX280 vs HD7770
That HARDWARE COMPARE implies that the GTX280 is theoretically "far superior" ;while I can't find a benchmark with BOTH of them in it, I did find THIS data:
Passmark Scores:
GTX280-> 1356
HD7770-> 2170
I'm pretty sure we'd find that the HD7770 beats the GTX280 in raw performance, and blows it away for power consumption, noise and simply being far NEWER.
**According to TOMSHARDWARE, the HD7770 is a tier above the GTX280 for performance so it would be closer to a GTX285:
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html