I have read many threads on these forums about if Anti-virus software is needed on a Mac or not. The general consensus seems to be that AV software is not required unless you work alongside Windows based machines and you are worried about passing a virus on VIA your Mac. The downside of running the AV software is that it tends to hog resources. But here's a thought. When I used a Windows based PC, I had the AVG software running, in the background, all the time that I was connected to the web. It would warn me of any potential threats. Also, once a day, it would do an update of the virus info and do a full scan of the PC. During this time the PC ran a lot slower than when the AV software wasn't running. But I also used AVG in another way. Whenever I downloaded anything from the web, for example, a film, I would always, always, always download it to a special folder on my desktop and then, before doing anything else, I would use AVG to scan the file for any nasties. THAT would be my one objection to the folk who say that AV software isn't needed. Surely if you inadvertently download a nasty from the web, even though it can't do you any harm, it's better to know it's there so you don't pass it on.