On a note with gaming, a 5770 was able to handle MW2, and Black Ops on all high settings except for AA off (I never play with AA, it presents a mouse lag). Take note that this with a AMD 965 and 3840x1024 resolution:
http://www.youtube.com/watch?v=Tqd1q1JPHyQSo anything a 5770 or higher is enough for gaming, unless you really want to get every frame of every second possible. I honestly don't notice a difference between the 5770, 5870, 5970, or currently CF 7970's in regards to fps and image quality on the latest games.