For years, Mac users have operated immune from viruses without anti-virus software. Now, increasingly, we're being told that Macs get viruses. Should we worry? The answer is, unfortunately, yes. Whilst Mac OS is still much more immune to attack than Windows, Apple has itself recently started to make noises that it would be a good idea for Mac users to protect themselves with anti-virus software. "Why now?", you (and I) ask. Well, the fact is that Apple's share of the home computer market has increased dramatically over the last few years. Once upon a time, Macs were largely used by well-informed geeks. Now, they're mainstream kit for the discerning computer user.
That means, on a very basic level, it is now worth targeting Macs because there are more of them being used by more people. What is widely believed to be the first Mac OS virus was discovered in 2006. Called "OSX/Leap-A", it was spotted hiding itself in Instant Messages (IMs). This really shocked the Mac community. In addition, Macs have been targeted by so-called "malware" (including spyware) for years. Before you dive headlong into this, though, bear in mind some of the basic terminology so you know what the various 'anti-virus' packages for Mac purport to protect: Spyware is malicious. It exists to collect information about the user of a computer, be that financial information, perhaps, passwords or other sensitive details.
Trojans are a non-replicating piece of malicious code which doesn't infect other files. It generally provides some access to a system via a 'back door'. "Key-loggers" which log key strokes to steal passwords, etc, are often called Trojans.
Viruses infect other files with their code, attaching itself to that file and often causing some form of damage. Whilst the infected computer may have 'symptoms', some viruses operate surreptitiously There are a range of Mac anti-virus and other internet protection options to choose from. But, it's a big step for most Mac users so I was interested to read more about this. There are a variety of useful sites, including Virus Protection For Macs.
Ultimately, you need to assess the possible risks against the cost of buying software to do the job. Also, you should consider the impact of that software on your system: will the software slow it down more than a virus?! Obviously this is a little "tongue in cheek", but with certain products on Windows in the past, that has almost been the case. The new breed of virus software on Mac OS does NOT fall into that category and is, from what I've seen, useful. It definitely has its place and will do increasingly - the threat level is increasing. Good luck.