I second that.
I'd also recommend looking for Internet security, the difference between Anti-virus and internet security is that internet security has a built in firewall and instead of letting threats come straight into your system, it has a chance to get them before reaching your system.
After what i have heard from my professors: There is no anti-virus software that is so much better than Avast! or AVG that its worth spending money on. Personally i dont know the difference, though im not saying there isnt one.
Me, i use Linux.