Three words - "Free Trial Version"
Even if your ISP bundles in virus and malware protection, I'd still get a standalone product for your PC. It's cheap insurance. I have a subscription for both products. I don't look at them as options, they are absolutely essential. Even though I backup regularly, If my machine goes down it will take a lot more than my $100/yr subscription fees to fix the problem. And that's not including the lost productivity.
Brad