the mac os is very unsecure. It’s just not been worth exploting it untill now. The newer versions snow leopard, lion have av built in. Google the phone that wells-f called you on, that should give you a heads up on if the call was a fraud.
The "security by obscurity" canard has been shot down many times before. The Mac is very secure and there ARE NO self-installing, sec-replicating, self-transmitting computer viruses for Mac OSX in the wild and crackers have been trying to write a successful one for over ten years and have yet to succeed.
You are right, there is anti-Trojan ability built into leopard and Snow Leopard and OSX will recognize the five falimies and the eighteen known Trojan horse applications that are currently in the wild and warn an unwary user before he or she downloads, installs, or attempts to run one,
Wayne, just how many OSX Macs in the wild is the magic number to make them attractive to the malware writers? Ten million? Twenty? Thirty? Forty? Fifty? There are now more than 60 million OSX MILLION OSX Macs in the wild with probably more than 95% running bare naked of any antivirus ware... Sitting ducks... and no one has been able to breech that target to make a Mac spambot. A two week window of opportunity for a 2,000 member spambot is worth $50,000 on the black market. That's about $1.2 BILLION potential to the malware writers who can compromise the sitting duck Macs out there!