Free X Server for Windows?

The Famous Brett Watson writes "I'm the Acting Nerd for a nonprofit org that has old equipment and no budget, so Linux and other free-to-use software is vital. Linux is the hero of the server, but Windows is still entrenched on the desktop along with MS Office. An X Server for Windows would allow me to start the migration to Linux apps whilst allowing the mandatory dual-OS crossover period, but I can't find a free one. There was one called MI/X, but it seems to have recently undergone the nasty transformation from Free to Cheap. I refuse to believe that there is no Free X Server for That Other OS, though. I feel the perfect way to introduce Linux on the desktop is by stealth. Replacing the OS outright isn't an option sometimes, but if you start using Windows as just an X Server, there comes a time when you can replace it with XFree86/Linux directly, right?"