I need to find infected computers on my network.
The easiest way would be to use AVG Antivirus 2011 Business Edition, which is not free. It can be set to a background Auto scan that can not can be canceled by a user, and I am fairly sure it can be set to notify your local CERT department if the scan shows malware.
Also using it in combo with Immunet protect will give you better protection from Web based malware attacks.
There is no free solution that I am aware of to saftware a entire network for general infects. Although, If you are looking for a certian type of Malware on your network, there are free tool to scan a network scan. SOPHOS (http://www.sophos.com/products/free-tools/free-security-scans.html), McAfee (http://www.mcafee.com/us/downloads/free-tools/index.aspx), and Symantec(http://www.symantec.com/security_response/threatexplorer/azlisting.jsp) all have free tools that can be used to scan a network and remove to threat, if you now exact what the threat is.
did you try the suggestions above or did you figure out another way to scan network computers for malware? Please let us know how you decided to do it. Thank you!
EMCO Network Malware Cleaner
Scanning your network for infected computers might be a bit of a challenge.
If you have access to the infrastructure you could setup a SPAN (Port Mirror) from the port going to the Internet line and scan outgoing traffic for known Virus or Malware traffic. The other option is to scan all shared drives on your network for Malware.
Neither option will give you the exact infection level of a single machine, let alone the entire network.
The only option to protect and overview all computers is to install an AntiVirus Software with centralized management (Remote Administration) on every single machine.