When upgrading the fglrx driver, don’t get lazy about removing the previous version. Besides the old configuration possibly still in use after a reboot, you get serious memory leaks in Xorg caused by the ATI Catalyst driver that resemble the same leak you get when using the driver provided by envyng.

Removal and installation is really straight forward and there is only a few extra steps. I keep my drivers in separate folders for each version. All commands are displayed as if you were in the working folder for that driver and ONLY that driver version.
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