free commercial-use Antivirus solution (Win2003,XP...

Hello,
I work in a small corporation / Enterprise and I have been searching for a free commercial-use Antivirus solution that includes an on-access real-time scanner (Hard Drive & Internet), e-mail (Outlook) scanning support as well as being able to update it via the Internet.

I have a Network domain that consists of one (1) Windows 2003 Server Standard Edition R2 (Domain Controller/ DNS/ DHCP / File Server) and thirteen (13) Client PCs using Windows XP PRO & Windows Vista 32-Bit Business. So I would need the Antivirus to fully support these operating systems.

So far, the only free for commercial-use (supposedly) Anitivirus solutions that I’ve been able to track down are the following, but I have no idea whether they will be able to fully cover the above said tasks?
Has anybody else here tried them and if so, how well do they perform?

Comodo AntiVirus Beta 2.0
http://antivirus.comodo.com/faq.html
http://antivirus.comodo.com/features.html

PC Tools AntiVirus Free Edition 4.0 - New Version
http://www.pctools.com/free-antivirus/
http://www.pctools.com/info/eula/product/anti-virus/
http://www.pctools.com/forum/archive/index.php/f-10.html

BitDefender
http://www.bitdefender.com/site/Downloads/browseEvaluationVersion/2/

Any help or suggestions on these Antivirus programs (Or any other that I’m not aware of) will be highly appreciated.
Thanks in advance.

 

Why would you want free software in a business environment. You could try avira, avast or AVG.
http://www.free-av.com/
http://free.avg.com/ww.download-avg-anti-virus-free-edition
http://www.avast.com/eng/avast_4_home.html

Good luck!!!