nVidia just dropped their WHQL (officially supported) release of the 275 driver today with 275.33. This comes after the 275.27 beta driver which was stated in the release as having caused a significant drop in FPS in The Witcher 2. 275.33 is the first official release in the 275-279 series of drivers, and offers many improvements over the 270 series. Most notable are the performance improvements in the 400 and 500 series cards with games such as Crysis 2, Portal 2, Batman: AA, Bulletstorm, and Civilization V seeing FPS improvements. If you're running old drivers, it looks like now is the time to get yourself updated with this new official driver.