VMWare! Woohoo We like VMWare in my house. We usually have 3-4 virtual machines running at any one time including the web server(s), and have a selection set up and ready to go if we need them.

Some of the the operating systems we run on a regular basis on both virtual and real PCs are Sabayon Linux, Gentoo, Windows 2000, XP, SUSE, CentOS, Ubuntu, DSL, Mint, Freespire and Windows 98, so we have plenty too choose from when we need a perfect OS for a task.

We used to run Red Hat 9 as well, but thats a bit old now. Most of the Linux ones run in virtual machines and do something website related or have done in the past.