I use Avast, Ad-Aware and Malwarebytes. I also run as a standard user with a strong password on the Admin and User accounts. I have a firewall on my router and the Windows firewall.
Your greatest protection is you. Unless you trust the source, don't open/download/install/click things.
When something says you have a gagillion viruses and for only $19.95 they'll fix it for you RUN! You are not the winner of a brand new iPod, I don't care what they say. You can see breasts anytime you want for free without signing up for anything so don't. You did not win the Nigerian lottery. Limewire is a free virus download service, get rid of it.