If you're having trouble with your ATI card, please post the following:
Video Chipset
Processor
Motherboard
I have two ATI systems (4870 and a 6950), and they both run the game well. If you want help, post your specs. If you want to cry and whine, then give the Add Reply button a break.
1. define trouble
2. define "run the game well"
HD5870
Q9550
ASUS P5Q Pro
Video drivers: Catalyst 11.5 Hotfix RC3
Trouble: FPS down to 30 and below on some sceneries, especially on container city, textures and shadows on high, rest disabled via Brink Config
Just a hint, everything below 50 FPS I wouldn't call "run the game well", with all due respect.