Trying to make Blender run smoothly on ATI graphics equipped machines is like trying to win a dragster racing challenge riding a bike: you're gonna loose for sure.
Well, at least any attempt was going to be a failure until a brave-hearted BlenderHead (a very crazy one, believe me) fell accidentally upon the solution.
I have to admit that the first time I've read what he managed to do I thought it was one of those "don't do it at home" things, but looking at the positive feedback he got on his Elysiun thread I was encouraged to publish this issue here on BlenderNation.
Worth have a try before throwing your beloved graphics card out of the window.
P.S.: Win32 only stuff, I reccommend to people living near Blender users who run on Linux to put on an helmet when they go outside for a walk , it will start raining ATI products soon ;-)