How can I install older proprietary drivers on Xubuntu 11.10?

view full story

http://askubuntu.com – I have a compaq nx7010 laptop, with ATI Technologies Inc Radeon RV250 [Mobility FireGL 9000]. This page seems to say that my graphics chip is still supported. However, Settings -> Additional Drivers is empty, and has the title 'No proprietary drivers are in use on this system'. Whenever I play a youtube video full-screen, the framerate is really low. I was wondering if a proprietary driver would solve this issue? Thanks (HowTos)