So far it remains true that we need a virus for the antivirus to protect against.
There is some malware and trojans but all the ones I know of are installed by the owners willingly. Not one installs on its own.
For example it is possible for folk to go to shady/blacklisted sites for free software like http://www.mywot.com/en/scorecard/sharewareplaza.com and INSTALL something bad.
Bad apps are not "virus". They are just bad.
I just read that there is a Mac virus going around. The article mentioned that it had injected itself (is that right?) into Graphic Converter 7 but might be part of other applications as well. It didn't name any. In one of the articles I found subsequently, there was mention that there are several anitvirus programs for Macs, including a free one from Sophos. No other one was mentioned, but I am wondering whether it might not be a good idea to put one on my Macs.
I have both a G4 desktop Mac running Tiger (OS 10.4) and a laptop with Leopard (OS 10.5). I've noticed some slowness (said to be a sign of infection by the virus), but I have no Graphic Converter. I also put much of the slowness down to my ISP being overwhelmed. I have changed my email address and shall soon part company, altogether, with my old ISP.
Any advice or further information, anyone? Thanks.