Well, that was fun... NOT!

Uh... I think I just infected my system by... downloading Windows critical updates. O.o;; I already had SP2, so it was just some updates, but after the reboot, my virus software stopped coming up with the system and I couldn't access the internet.
Tried for over an hour to figure it out and finally ended up doing a system restore. It doesn't seem likely... but I'm afraid to try it again.
Anybody else had any trouble?