Let's hear from Prez Art Gorski, "Here's a quick review of anti-virus applications for the Mac. I won't be installing any of these myself, but if you're worried about malware and don't mind the overhead of running this kind of software, give one of the free ones a try."
Read about these 5 apps; two are FREE, and the others run from $39.95 to $49.95 a year.
This is just in from Bobbie Pastor about Sophos, "This is a free download for your Mac. John Carter considers this a good product." See it here.