Mac 101: User Accounts and Basic Security
While there are no true viruses for OS X, that doesn't mean Macs are impenetrable. They're still vulnerable to malware, spyware, spam and trojans. However, with just a few precautionary measures, your Mac can be more secure than most any other consumer technology out there.
http://feedproxy.google.com/~r/TheAppleBlog/~3/-O_KGowaivM/