My god, don't you people know when you're being scammed???
Windows has become solid enough with Win7 that the so-called "security vendors" and anti-virus salesmen are desperate for revenue. Some (like Symantec) are diversifying into other services... some are saying, "Well, who else can we scare into buying our products??"
And the Mac is just the next one down the list after Windows.
Show me the Mac viruses.
Not the generic human-engineered malware that can affect any computer with a gullible operator. The Mac viruses, self-replicating, the ones that a human can't defend against with simple common sense.
Don't prevaricate. Show me the Mac viruses.
Otherwise, take these anti-virus products and shove 'em, until such time as there's something to protect against.