I came across some of the recently released VMWare Free Virtual Machine pre built ‘drives’ recently. One of the most interesting was a binary compatible WindowsXP clone called ReactOS.

Some other pre built OS’s worth looking at are

• IPCop – Linux firewall
• Squid – Linux proxy / reverse proxy server
• Fedora Core Test 5 – Linux distro

There are many others at the VMWare page listed above.