follow the steps outlined here:
http://support.amd.com/us/kbarticles/Pages/GraphicsDriv...
You should be able to download the drivers from here:
http://sites.amd.com/us/game/downloads/Pages/radeon_win...
This assumes a 64-Bit OS. Use this link for 32-bit Windows 7
http://sites.amd.com/us/game/downloads/Pages/radeon_win...