The version of radeonhd in the repo should be sufficient, but if you want the latest version of the radeonhd driver, build it yourself or use https://launchpad.net/~tormodvolden/+archive/ppa
The radeonhd driver supports video cards based on the following ATI chips:
M86 Mobility Radeon HD 3650, HD 3670, Mobility FireGL V5700
Building your own: https://help.ubuntu.com/community/RadeonHD
Option "AccelMethod" "EXA"