This is going to sound like a sales pitch, but I assure you I am not being paid by Sophos to say this.
I'm not talking about bleeding edge definitions for variants that just came out the day before the switch either. I'm talking about stuff that's been sitting in temp for months in some cases.
If you are curious how it'd do in your environment, download the free removal tool and run a one time scan of your system. or sign up for a trial of the full thing. It really does find stuff that the other guys miss.
Sophos doesn't have a home user product like most of the other antivirus companies, but even for small businesses they have packages that are fairly affordable, especially if you bundle several products. With our government pricing we managed to get a replacement for our antivirus including e-mail servers, plus a spam appliance as a VM and mobile device management, endpoint encryption, and a few other things for about what we were paying for maintenance on the anti-virus parts with another company.