I use Norton AV on my mac & AVG on windows. Not that I really need one on my mac, but better to be safe than sorry. And I'd prefer not to pass on viruses if there's any connected to any windows file I downld. Whilst Mac OSX doesn't have viruses, the earlier OS's did have some. And I found a couple of those ... only one infected me (after which I got an AV.)

BTW TamTheBam is busy trying to discover what the heck that is under his kilt. Though he'll need to put his glasses on as he can't see it very well ... well apparently there's something there. Frostbite perhaps!