I dunno... I recently had a very bad experience with upgrading / downgrading Radeon drivers which took around 4 hours to resolve including editing Windows Registry (not recommended for the feint of heart). Got my Radeon HD 5850 up and running again, but the issue I was trying to fix "Video Drivers Has Stopped Responding And Has Recovered" was not resolved for Skyrim. I didn't matter if the game was vanilla or modded. Somewhat frequent with Civ 5, but absolutely doesn't happen with Mass Effect 3, GTA 4 or Tomb Raider.
I thinking about switching to nVidia... but not sure yet...