Avast! - Great detection & low memory use

Avira AntiVir - No email scanner; update nag screen

Sophos - Good detection in a free anti-virus app

Prey Project - Better than FindMyMac, use both for best chance of recovery

Anti-Virus

Yes, Martha, Macs DO get viruses. In Spring 2012, nearly one million Macs globally were affected between two virus outbreaks. As Macs gain market share, they also gain more attention from hackers.

A good, full-time anti-virus program is the core of your computer security and helps keep the nasties from getting on your computer in the first place. Make sure you only use only ONE of the these.

Mac Security

Bitdefender - One of the best comes to Mac

When you pay that much for a Mac, you really, really want to know where it went if it goes missing.