From somebody that switched from a Nvidia card to ATI, stick with Nvidia. There are so many performance issues with ATI cards and new releases.
I thought the days of hot fixes whenever a new game comes out were over, but that's how the world of ATI still works. However, to be fair, most of the hot fixes are to fix crossfire (multiple GPU) performance issues. So running a single ATI GPU setup might provide a better experience.
Posted via RS Mobile