Last week's TidBITS has a great set of tips from Rich Mogull to evaluate Mac security claims, as to whether they're worth concern. (Some are.) Not sure how I missed it when it came out, but John Gruber highlighted it. The basic questions:
While a lot of claims of Mac vulnerabilities, exploits, viruses, and trojans are questionable, Mogull notes that, "The latest version of Windows (Vista, not that most people use it) is provably more secure in the lab than the latest version of Mac OS X 10.5 Leopard."
Incidentally, TidBITS is turning 19 this month—it is one of the very oldest Internet publications that has continued to operate that entire time. It remains a valuable resource for techies in the know. I can't even recall when I first subscribed, but I must be somewhere around 15 years as TidBITS a reader myself.