And your question being what exactly?
I believe in having the latest drivers to avoid problems with games that are new, if any.
As for performance: a driver rarely increases performance to the point where you clutch your desk (pillow or whatever) and get whiplash.
Some instances, like Xfire and the OpenGL driver enhancements, you'll notice some change - but that's like a commet flying past in the northern hemisphere with you sitting in the southern hemisphere - alot of people claim to see it, some don't and some don't care as long as the commet missed earth. In other words, it's trivial except for the guy working with fractions as a measurement tool for performance.
As for stalls and crashes, I doubt whether the driver is to blame, as Nv and Ati have pretty secure drivers even with the driver in Kernel mode - most likely it's somewhere else in one of your pc's subsystems where something goes wrong.
BUT, giving exact details of stalls and freezes once again will help you alot more in getting answers...