If you think you don't need an anti-virus software for Mac then you might regret your decision taking chances with your data and privacy, although very limited but there exist viruses for Macs and to get protection from these baddies you need an Anti-virus solution, luckily like Windows there are quite a few good free anti-virus software's available for Mac OS X, PCTools iAntiVirus and ClamXav are two such free solutions for your Mac computer.
PCTools iAntiVirus is very simple to use with minimal options, the free software provides efficient real-time protection with automatic smart-updates.