Four free, self-contained antivirus tools:

 avast! Virus Cleaner
 http://www.avast.com/i_idt_171.html

 Stinger
 http://vil.nai.com/vil/averttools.asp#stinger

 TrendMicro Sysclean
 http://www.trendmicro.com/download/dcs.asp

 F-Prot Antivirus for DOS
 http://www.f-prot.com/download/home_user/

 Panda AntiVirus
 http://www.pandasoftware.com/download/utilities/