Hundreds of Free Virtual Appliances
VMWare has a community site that provides hundreds of Virtual Appliances for use in their free VMWare Server product. What is a virtual appliance? It is a preconfigured operating system that has been tailored to perform a specific set of functions. There are appliances for Ruby on Rails development, Python Web Development and even Jabber servers. Virtual appliances make great test development environments and allow you to try a wide range of services without the pain of installing the systems yourself!
For Network Monitoring and Security virtual appliance that can monitor IP networks including VoIP calls with features such as
long-term data mining, full packet capture, analysis and powerful
reporting and analysis.
It’s available for Free Trial
http://www.intelicanetworks.com/virtual_appliance.shtml