Anti Virus For Free

Avira AntiVir Personal Edition Classic.
Avira offers a free anti-virus software is equipped with protection against viruses, trojans, backdoor programs, worms, etc. 
Free Download

AVG Free Edition
AVG is equipped with a resident shield, email scanner, anti virus / trojan. Not heavy on running on your computer.
Free Download
Update AVG Definition March 12, 2010

AVAST Home Edition 5.04.62
AVAST Home Edition 5.04.62 offers anti virus, worms, trojans, boot-time scanner, features a screen, saver anti virus scanner to make it to work as a screen saver.
Free Download

BitDefender Free Edition Build 2009 12.0.12.0
BitDefender Free Edition Build 2009 12.0.12.0 is also equipped with anti-spyware and offer updates every hour.
Free Download

RemovalIT Pro
RemovalIT Pro is a free antivirus that can detect and remove spyware, malware, worms, trojans and adware.
Free Download