I added this ppa repo to my sources.list, upgraded and my glx gears went from ~2870 to ~4880. This repo was recommended on the Ubuntu Forums for possible performance improvements. It’s Xorg, so beware. (I’ve used it before with 9.04 and never had problems, Nvidia Quadro that time)
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 8844C542
I’m using Karmic 9.10 x64 on this Dell Vostro 1220 with an Intel x4500HD graphics card.