Well, back on OS 7, 8, and 9 I ran into virus trouble all the time (though not as much as Windoze users, heh heh heh). What was it... MDEF something or other? Anyone remember the one with an M that came in several strains?
Anyway, with my .Mac account I get Virex for free, but I don't use it. No problems since X revolutionized my life.
I would have to say don't worry about it.
Dan