This used to cost bucks, but it's now free. Why?
As Microsoft releases its Windows hypervisor technology in the Windows Server "Longhorn" wave, customers will be receiving the benefits of virtualization as part of the Windows Server operating system. Today’s price change makes it easier for customers to access and experience the benefits of virtualization technology.
Umm....yeah. Basically, the next server versions have better stuff included, so might as well give away the current technology. I think.
Anyhow, go get yours: http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx. RAM is your friend (seriously--get as much as you can).
This is the version which supports Linux. Maybe. See image below (original document at http://www.microsoft.com/windowsserversystem/virtualserver/evaluation/linuxguestsupport/default.mspx).
