For those that do not like Norton AV taking over their computer I have used eTrust EZ Antivirus and the predecessor called InnoculateIT for over 2 years.
http://www.my-etrust.com/

Used to be free for personal use but for ~ 1 year is $20.00 to purchase plus updates for a year and after that $10.00/year to renew. Free 30 day trial to see if you like it. I just use it, not involved with the company.