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.

It features:
High detection rates for viruses and spyware;
Scanning Scheduler;
Automatic downloads of regularly updated Virus Database.
Standalone virus scanner and right-click menu integration to Microsoft Windows Explorer;
Addin to Microsoft Outlook to remove virus-infected attachments automatically.