
OS X comes with a firewall which I believe is turned off by default. Personally I've never bothered with software firewalls, even under Windows and prefer to rely on the firewall in my router.
You don't need any AV software at all for your Mac. Have a look at this thread where even though someone claims that there are viruses, despite being asked to tell us what they are, he doesn't manage it.
Oh, and you don't need any defrag software either![]()
this is my first mac using it as my second computer. 
this is my first mac using it as my second computer.![]()

