It seems that the binaries from http://ati.amd.com/support/driver.HTML don't work with rt-kernels (http://www.linuxmusicians.com/viewtopic.php?f=6&t=890).
This solution was already posted in the link above, but I re-post it here because it may be useful for other people to have it more visible in the howtos section.
In my case the main aim for getting the ati card working is that I could not use resolutions higher than 1024x... with the default 'vesa' driver.
In this link http://www.phoronix.com/forums/showthread.php?t=9951 it is explained the solution that worked for me (and also for others in this site).
I only followed steps 1 and 4.
These steps are for Ubuntu. For Debian, just edit sources.list when asked to add new repositories.
Good luck,
Gerard.
kernel-rt and ATI radeon
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