ClamWin is a Free Antivirus program for Microsoft Windows 98/Me/2000/XP/2003 and Vista. ClamWin Free Antivirus comes with an easy installer and open source code. You may download and use it absolutely free of charge.
AVG Anti-Virus Free Edition 8.0 Basic antivirus and antispyware protection for Windows available to download for free. Limited features, no support, for private and non-commercial use only.