In the past, there were virus's for mac, but very rare. Sometime agin, I recall one that 'nestled within Microsoft Word. That was quite a few years ago. Then there was an occasional, what they call 'malevolent.' html. They were not that serious. Until now, I've never had a virus. But don't kid yourself. They are being developed for the mac, and sooner or later, they will be openly noticed.
When someone writes a virus, they usually have to destroy a machine in the process. MAC's, being so much more expensive, and the architecture of the os what it is, made writing a virus much more difficult and expensive. A lot of the guys writing the virus's, were young, in school, and had not lot of money to destroy a machine to write one. With the pentium now in the mac, and with pc's and mac's getting closer in other ways, and the costs somewhat coming down, the possibilities and availability are making it easier.
I don't want to argue the point, but as you, I never had virus protection until now. I would not be getting a program, after all the years I[ve used mac, unless there was a reason. There is. I am not interested in forcing such an idea, I am doing what I am doing by having AV, because I see the need coming.
Anyway, even if you are TOTALLY correct, i still have the issue with SOPHOS.
This one I'm using is an older mac. I use it primarily for graphics, video and music editing.
Last crop of the dual mirrored door G4's. 2 gigs Ram 1.25 ghrz processor. 'Three hd drvs. two optical drives, one burner, and It's in great shape. I have a forth drive running Linux.