I use Virtual Machines all the time - any time I need to develop or test something I fire one up. I used to work with VMWare's products, which I really like. Lately I've been using Microsoft's Virtual PC, but I just saw a new book on Xen, the Open Source VM software.
Of course, all three are free, at least the lower versions that I use personally. I haven't played with Xen, so I'm reading a new book that just came out on it. You can check that out here: http://www.informit.com/store/product.aspx?isbn=0137144911&f1=rss
Which VM software are you using, if any at all?
Take advantage of special member promotions, everyday discounts, quick access to saved content, and more! Join Today.