Install the xorg-driver-fglrx package from the Restricted repository (see Chapter 2, Adding, Removing and Updating Applications).
You now need to configure the computer to use the new driver so run this command in a terminal:
sudo dpkg-reconfigure xserver-xorg
When the dialogue appears and asks whether to do automatic detection of your video, pick Yes.
When asked to select a driver, pick fglrx.
Follow the remaining instructions as appropriate.
Restart your machine for changes to take effect.
Run fglrxinfo to see if the driver loaded
thanks to notbad on the overclockers.com forums!