Free Antivirus

Freeware Antivirus Comparison
http://wiki.castlecops.com/AntiVirus_Comparison

Avast! 4 Home Edition
http://www.avast.com/eng/download-avast-home.html

AVG Anti-Virus Free Edition7.5
http://free.grisoft.com/doc/5390/us/frt/0

Avira AntiVir PersonalEdition Classic

http://www.avira.com/en/pages/index.php

Comodo AntiVirus
http://www.comodo.com/products/free_products.html

ClamAV release 0.91.2
http://www.clamwin.com/content/view/18/46/

McAfee VirusScan Plus Special edition from AOL
http://safety.aol.com/isc/BasicSecurity/

BitDefender 10 Free Edition
http://www.bitdefender.com/PRODUCT-14-en--BitDefender-10-Free-Edition.html