Pretty straight forward, depending on what your current version is.
For that card, I would use the Catalyst 4.12 drivers. The 5.x drivers re-introduced a very old ATI bug which causes the radar dots on the clipboard to always be black.
Just avoid the Catalyst Control Center at all costs. Use the ATI Control Panel instead. Your computer will thank you.
1) Download the driver installation files from ATI's WEB site (
http://www.ati.com).
2) Use the Windows Add/Remove Programs ICON to remove the current ATI drivers and control panel (they usually have to be installed together as ATI keeps adding features to the control panel).
3) After the reboot (you will be in VGA mode, dunt panic as it is ugly and slow), run the file you downloaded from ATI's WEB site and you should be good to go.