AVG = Way too many false negatives. A high chance of deleting DLL's and EXE's you need. When AVG says something is a Virut , It is lying. Because of AVG I have to install windows every 5-10 days. To me its the most horrible anti-virus I've even seen. The only reason I use it is for the firewall.
I use Malwarebytes' Anti-Malware, Norton, Ad-Aware SE personal, RegCure, and AVG. All of them find something different.
Norton scans very slowly, and still miss infections. My CPU is going through DLL hell right now. RegCure finds like 9800 problems, and "fix" them. It don't fix a damn thing. Malwarebytes' Anti-Malware kill viruses, But they just come right back. I'm at the point where I don't want to get online anymore, well not with my computer.
From what I know: viruses hide in system32, windows folder, and a hidden folder called "temp." etc