Steve has a Mac and wants to know if he really needs an antivirus utility. Leo says that the bad guys have slowly begun to write exploits to take advantage of the Apple platform. This wasn't the case a few short years ago, but as Windows users have gotten better at locking down their systems, the hackers have to go somewhere. So the short answer is yes.
Leo recommends Eset's CyberSecurity for the Mac. (Disclaimer: ESET is a sponsor).