Antivirus on a Mac? Why waste the money and memory resources? As the OP stated there ARE NO OSX viruses. Zero. When I see JUST ONE, maybe I'll think twice, but until then...
Most infections in the windows world come from email attachments, and from surfing "naughty" sites. Due to certain surfing habits nasty malware of some sort always found it's way onto my windows machines. EVIL things like winfixer that are self healing and generate self-repair files under random names in weird places then run as part of explorer or IE so you can't get rid of them (at least without a MAJOR effort).
I got used to regular reformats / reinstalls, and just accepted it.
After over a year of HEAVY internet use on my macbook, I have had not ONE single issue, ever.
Bottom line, there is no OSX virus. It doesn't exist.
Some will say, "that's because macs aren't that popular", but that is an illogical argument. Let's say that windows machines outnumber macs 6 to 1. With thousands of known windows viruses, there should still be well over a thousand mac viruses, just looking at probability. But yet there are ZERO. You are telling me that nobody has ever tried? I don't buy it.
Yeah, macs are a less appealing target due to market share, but by the same token being the first hacker to devastate the mac community would be a big feather in any hackers cap right?
Straight up, if you like to spend hours surfing every corner of the net you just can't beat a mac. Mac = internet the way it was meant to be.