Windows ships with a number of drivers of course (otherwise it wouldn't even be possible to install or boot the OS), which including things such as standard IDE controller drivers, basic sound and video card drivers, and whatever WHQL certified drivers where on hand when the retail OS build was finalised. Since the Radeon 8500-series pre-dates Windows XP, there will be the last WHQL certified driver included. Support software, such as the ATI Catalyst Control Panel or Control Center, is never included. You'll probably find however, that the Microsoft supplied Radeon 8500 driver is not fully accelerated. You should install ATI Catalyst.

Returning to the issue at hand however, I believe that your best option at this stage would be to reinstall Windows.