www.johnsdesign.net; linux.

VmWare has released a free player, for community/vendor built virtual machines. There's also a server version going through beta testing. They both run off of Windows 2K/XP and Linux.
Also available are what's called live cd's. The most common is from Knoppix. I've had fairly good success using old PII 350-450mhz white boxes; these boxes generally use pc100 ram, which is fairly easy to find used (and cheap). There's no need to tie up a hard drive either, since the Linux OS runs straight from the burned cd.
Frozentech has a good list of other linux based live cd's.
Red Hat's open version of their linux is located through the Fedora Project. Mirrors and BitTorrets are available.
Novell has made SUSE open as well; it can be found through OpenSuse.
Gentoo, Mandriva, Freespire, Puppy Linux and Ubuntu are also available.

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