If you have all of the Windows updates, there's no reason for viruses to just appear on your computer while you play a game with your virus scanner turned off. If you're paranoid though, disconnecting your PC from the internet should be enough to stop any viruses.
As for this crashing update... it looks promising, but I still don't think it's the whole story. If this is a Norton problem, why do these Nvidia crashes only occur with The Sims 2 and not any other games, or any other programs at all? Why would a memory leak in Norton, a program that has absolutely nothing to do with 3D graphics, cause the graphics driver to crash anyway? And why isn't it affecting any other brand of card?
If this does solve the problem though, I guess a fix is a good thing, even if the real cause of the problem is still a bit of a mystery
