truly free virus/ad remover?

where can i get a true free virus removal tool…one that does not want to take up residence in my computer, i tried housecall and it says it can’t remove some adware…so i removed the adware 2007 from lavasoft that i had installed thinking that was the problem and ran housecall again and i still get the same back from housecall. anyone got some ideas on how to truly get rid of the crap??

Google offers a free version of Spyware Doctor through the googlepack that is excellent at removing adware/spyware.

http://pack.google.com/intl/en/pack_installer.html?hl=en&gl=us

when selecting items to install from Googlepack, if you only want Spyware Doctor, uncheck all other items listed.