I have got Ati Mobility radeon ,open source driver and Gallium 0.4 on RV 630. This open source driver is not powerful. I downloaded driver from AMD web page and at the beginning of the installation I received this:
Check if system has the tools required for installation. fglrx installation requires that the system have kernel headers. /lib/modules/3.8.0-19-generic/build/include/linux/version.h cannot be found on this system. One or more tools required for installation cannot be found on the system. Install the required tools before installing the fglrx driver. Optionally, run the installer with --force option to install without the tools. Forcing install will disable AMD hardware acceleration and may make your system unstable. Not recommended.