Short description of MSN Sniffer 2: MSN Sniffer is world's first sniffer to automate MSN chat capturing and impact analysis. After installed on one computer, it captures MSN chat across all computers in the same LAN, analyze and save into database for future analysis. msnsniffer.com
It is very easy to make it to work. Just run the MSN sniffer on any computer on your network, and start to capture. No additional program installation is needed on the monitoring target computers.