I am using ClamWin Free AntiVirus, I hope it works for you, too. It is
a GPL anti-virus.
You will find it here:
http://sourceforge.net/projects/clamwin/
---- About ClamWin Free Antivirus----http://www.clamwin.com/index.php
ClamWin is a Free Antivirus for Microsoft Windows 98/Me/2000/XP/2003.
It provides a graphical user interface to the Clam AntiVirus engine.
ClamWin Free Antivirus uses the GNU General Public License by the Free
Software Foundation and is free (as in freedom) software.
....
ClamWin Free Antivirus comes with an easy installer and open source
code at no cost. It features:
* Scanning Scheduler;
* Automatic Virus Database Updates. ClamAV team updates Virus Databases
on a regular basis and almost immediately after a new virus/variant is
out;
* Standalone Virus Scanner;
* Context Menu Integration to Microsoft Windows Explorer;
* Addin to Microsoft Outlook.
Please note that ClamWin Free Antivirus does not include an on-access
real-time scanner, that is, you need to manually scan a file in order
to detect a virus. Microsoft Outlook Addin and POP3 Proxy (coming
soon), however will delete a virus-infected attachment automatically.
--------------http://www.clamwin.com/index.php-------------