I had one once, but on a computer bought several years ago and has since been reformatted and sold to someone else.
I Use Panda's Antivirus since then.
A funny story, the computer that got infected was a dell, with a free brief subscription to McAfee Antivirus. When I got the virus, I called McAfee for support, the tech I talked to, recommended That I switch to either Panda or Trend Micro's PC-cillin. Never had a problem since. So, at least, if McAfee's product was completely ineffective (and it was) at least their tech support is good. 😛