No less stable than usual...
I'm using 285.27 beta driver with my GTX 460 and CS 5.5.1. No problems so far.
Note: These are for Seven/Vista. If you need driver for different OS please start here:
Updated to 285.38, no problems with the updated driver.
i put 280.26 on and the opengl errors seemed to be gone.
I use Quadro FX 5800 with the latest driver (275.89 atm).