How do clean a virus from a computer?

Run a virus scan using AVG free (can download at web address below) and then at the end of the virus scan (can take up to 4 hours depending on hard drive size and CPU speed) and then at the end you should get an option to remove all viruses found or it should (most of the time) do it automaticly. http://www.download.com/AVG-Anti-Virus-Free-Edition/3000-2239_4-10320142.html?part=dl-AVGAntiVir&subj=dl&tag=button