I'm also having problems with debian and the ATI drivers. (Sorry about all the blabbering, but I'm trying to give as much info as possible.) I have a Radeon 9000 Pro, which is supported by the drivers. I installed the package on their site using Debian with no errors and ran fglrxconfig (which crashed the x until I changed the entry for the location of the video card from PCI:1:0:1 to PCI:1:0:0), but it acts like it isn't installed! modprobe fglrx can't find the module, the shortcut to the ATI control panel doesn't work, and fglrxinfo acts very strangely. When I access it as root (through su), it gives an error:
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
but as a regular user, it gives:
display: :0.0 screen: 0
OpenGL vendor string: VA Linux Systems, Inc.
OpenGL renderer string: Mesa GLX Indirect
OpenGL version string: 1.2 Mesa 3.4.2
which seems to be software emulation. I went through the readme from ati, also. What else could I do to get it working?