This is starting to sound like a broken record.... 🙄
I've yet to have a problem with virii in macs. Been using macs for about 15 years, and never bothered with anti-virus. I'm thinking of doing so now though, as it seems like we're getting more converts. Virus writers go for maximum impact, and with more people using macs, we could start to become a target. Norton will most likely do the job for you.