I used to use Norton and found it to be a huge resource hog and have switched to AVG. It used to be AVG Free, but I think there is a charge for it now. Along with that I use and run Spybot and Ad-Aware on a regular basis. (They are both free as well) For help with computers, and I mean just about
any help you could want, I found the folks at:
to be especially helpful. (I hope it's okay I posted that link?) I have no vested interest in bleepingcomputer, but I do know that those people are very good and make things easy for us who might not be so technically minded.
One thing: I always unplug my puters during thunderstorms. I've heard of folks having their motherboards etc. fried with one lightening strike.