I found this wiki page on cleaning up old drivers for your graphics card:
http://wiki.team-mediaportal.com/1_MEDI ... g_Playback" onclick="window.open(this.href);return false;
Scroll down to "Cleaning Drivers" Section for info. I was amazed at how much was left behind. I don't think it amounted to significant disk space but just to see so many legacy driver installs for ATI was a shock.