Steven Cohn has a nice hack for supporting multiple root websites on Windows XP Pro. You can’t do multiple simultaneous sites, but between this and the HOSTS file you can simulate any live site on your XP Pro box, which is a lot handier than having to remote into a Server install or use a virtual machine. (and of course, the reason this is an issue at all is that developing a site that resides in a domain root is a whole lot easier when you don’t have to try and switch between a dev environment that exists in a subfolder and a production environment that is in the root).
