im trying to uninstall my display driver, but whenever i restart my computer..it automatically reinstalls all the drivers, showing the "Found New Hardware" balloon. i need to install the new catalyst 5.5 over the older catalyst i had with ATI 9800 pro.

The standard method being:

Download the new drivers & Save to disk.

Then:
Boot the computer to Safe Mode options (F8 after BIOS) & choose:
"Enable VGA Mode".
Go to Control Panel, Add/Remove Programs.
Find your graphics card driver package & uninstall.
While in Control Panel, go to System, Hardware, Device Manager.
Expand (Click +) besides Display Adapter,
Right Click your graphics card, Choose Properties, Drivers, uninstall.
Reboot the Machine - It will re-detect your graphics card.
Then install the new drivers.