My anti-virus software?
Macintosh.
Been using Macs all day every day since 1995. Have never installed any kind of anti-virus software, and never had a problem.
For the amount one might spend on PC virus software, one can buy a Mac.
But, don't buy a new Mac from Apple, unless you really need latest greatest cutting edge features. Very few people need the latest models.
Instead, buy 2 or 3 used Macs. I do all my work on a 10 year old $79 Mac.
Here's the math.
One New Mac: $1000-$2000
Three Used Macs: $79 X 3 = $237.
Why buy three?
If one breaks, toss it, plug in the next Mac. Downtime 5 minutes.
Say goodbye to repair hassles and expenses once and for all forever.
I've used
www.macofalltrades.com to buy used Macs a few times, so far so good. I don't work or sell for them. All I can speak to is that they've treated me right a few times.