I just let the antivirus, antispyware, and antimalware update automatically, so I'm less likely to be infected by a new virus since I'm up to date on my updates.
I let it update; if It tells me to restart however... that's probably not going to happen. (My computer has this thing, that sometimes if shut off or restarted... I'll get stuck at the start screen. So I don't even bother and put it in hibernate all of the time to prevent it from getting stuck again)