Can't uninstall ATI drivers!

Hi!

My ATI Radeon 8500 is completely dead. I removed it from my
system, and installed my old Voodoo5 v5500 in its place.

Now there's a problem.. I cannot uninstall the old ATI drivers.
Trying to uninstall the "Control Panel", for example, doesn't
report any error BUT doesn't uninstall anyway. I also get windows
reporting errors on boot up.

My question is:
how do I uninstall (possibly cleanly, i.e. without hunting and
removing every "ATI" key in the registry) every thing related
with my ATI Radeon 8500 on my system?

Thanks!
Mike