I installed these last night and I have not encountered any problems. My frame rate seemed a bit higher in Half Life 2 and Doom 3. I also tested the new drivers with Star Wars Battlefront and Unreal Tournament 2004 and those also ran fine. I have an X800 Pro.
They basically took the business risk of creating this game and banking on the success of the 2nd and 3rd movies to make this game work. They took the risk and it certainly seems like they were wrong. I honestly dont see this game lasting more than a few months.