Yep,

Steam will auto update your game if you have this option selected.

I have updated and so far haven't had any CTD, but then I didn't before either.

I've just been playing my with my original campaign game from when the game came out and everything is working so far.

I am Athlon 64 dual core 4400 with a gt8800 2 gig ram Vista 32 prof edition sp1 if that helps, I know how frustrating it must be to everyone with a better specced PC than mine for the game to keep crashing, I had the same problem with GTAIV for about 4 months until windows live patched the game up so it would work with a workable framerate. All I can say is hang in there!