I don't normally use virus protection, but sometimes I need to scan my system before I'm allowed to connect to a client's network. On such occasions, I use Virex.
actually I checked mac's site last week and they said they arent offering virex right now because of some problems with the latest version...
if you have another link to download it let me know...someone mentioned that it should come with your computer, well I just got a new mac mini and it didnt