The power hungry Pentium III Linux computer you have running in the closet is a perfect candidate for a virtual machine conversion. Fortunately, it is possible to convert that computer into a virtual machine and ditch the energy hog. The Windley's Technometria weblog runs down the surprisingly easy (yet lengthy) process of converting a physical computer into a VMWare virtual machine.
I could have just rebuilt the whole machine from scratch on a new virtual machine, but that takes a lot of time and the old build isn't that out of date (one year) and works fine. So, I set out to discover how to transfer a physical machine to a virtual machine.
Mac users can virtualise and dual-boot the same partition — have your cake and eat it too!