When I first bought my iMac I downloaded an antivirus app straight away. I tried iAntvirus at first but for some reason I couldn't turn on "Protect My Mac" so I now use Sophos. Apparently Sophos is quite useless, I've heard it doesn't actually delete any threats :| I've had this Mac for months and I've had no problems. I did stumble across a Mac rouge antivirus (Mac Security or whatever the hell it's called) using google image search but I got out of it straight away as I knew it was dodgy. Really, is there any point for Mac Antiviruses?