One of the most effective ways of cleaning a computer heavily infected with viruses or malware is to Slave the computers harddrive to a good working computer with up-to-date virus scanners and malware scanners.
The reason for this is that working as a slave the infected operating system is not active so hopefully neither is the virus application. If the virus is not active hopefully it is easier to clean it off the infected harddrive.
One very useful device for doing this is a USB to IDE/SATA adapter capable of supporting both desktop computer harddrives and laptop harddrives. These adapters can be a little finicky to use first time if you haven't used one before. Please read the sticky in the harddrives forum for some guidance on using one of these adapters for the first time.
This link will take you to the sticky.
http://forum.pcmech.com/showthread.php?t=204049