I installed the new GPU client when I switched from an 8800 to a 4850 recently and I've had no real problems except one. When I try to play games now I have to manually shut down the client becuse it no longer detects that the GPU is in use properly. When I don't shut it down I get a distinct drop in frame rates in most games compared to when I don't have it running.
I never had the problem when I was running on nVidia hardware, it's only been since I reinstalled the client for my new ATI card. Has anyone else been experienceing anything similar?