Or if you regularly communicate with Windows users.
You may find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful: The User Tip seeks to offer guidance on the main security threats and how to avoid them.
Do I need Antivirus for new Mac Air and if so which is recommended.
In General 3rd Party AV Software is Not Required as Mac OS X tends to look after itself.
See here > http://www.thesafemac.com/mmg/