Go to support.amd.com and surf to /us/gpudownload/windows/Pages/radeonaiw_vista64.aspx (for Windows 7 64-bit).
I had been using 12.7b because I have dual 7950s in Crossfire mode, which under 12.6 Skyrim was totally unplayable. Gameplay was relatively stable under 12.76b until the 1.7 patch, and then Dawnguard, was released -- nowadays, I have CTDs in very specific places, usually at the boundary between two outdoor cells. I'm not sure whether the drivers are at fault, but since I read that many people were able to alleviate the symptoms by downgrading to 12.6 drivers, perhaps these new ones will help us all.