I've figured out how to install ATI's Catalyst 9.8 drivers with Debian Squeeze (testing) 2.6.30-1-amd64 #1 SMP. This was the thread the helped a lot with solving the installation problems:
However, there are still some major issues:
1) There is no way I can see the mouse pointer in full screen OpenGL applications. Both under wine or native. I've tried putting
Option "SWCursor" "false"
and no mouse option. Either way the mouse just disappears.
Option "SWCursor" "true"
2) It is almost impossible to open menu items when SMPlayer (MPlayer) is playing a movie in a window. Everything slows to a crawl. In order to be able to watch movies in full screen mode I've had to configure the player to use OpenGL.
3) Flash movies (for example, Youtube) are very, very slow. Fullscreen viewing is also impossible. I've googled a lot and tried to enable or disable HW acceleration, but there was no change. This happens with Adobe's Flash 10 under Iceweasel (Firefox) and Konqueror.
4) Compiz, while integrated into KDE4, is just useless. You can't select any kind of text, the mouse draws random squares on the screen and OpenGL apps just freeze the system or refuse t work. It must be turned off in order to provide a usable desktop.
5) The overall graphics experience is disappointing, to be polite. My older system had an old Atlhon XP 2000 processor with an old Nvidia 5200FX GPU. It felt more stable and a lot faster in 2D and 3D. My current system is an Intel i7 with ATI's HD 4890, lots of disk and RAM. I would expect the overall experience to be a little better than the old one.
I've bought an AMD/ATI card because of their willingness to help with open source drivers. However, I didn't have a clue about how crude and lacking their proprietary drivers were.
I still believe my choice was kind of correct and that there will be quality open source drivers sometime in the future, but I'm stuck with the current drivers for a while. Is there anything you guys know that can help to improve anything?