I’ve deployed a number of VMware installations for clients and have been reasonably happy with the results. I recently spoke with someone who advocated using Xen for GNU/Linux servers and Windows Virtual Server for Windows servers. I would agree that in an exclusively GNU/Linux environment that Xen is my preferred solution. However, most of my clients need both Windows and GNU/Linux servers and I would prefer them to be hosted on the same server. I also think it’s advantageous to use only 1 virtualization solution for an organization, especially smaller organizations. At home I’ve been using VirtualBox OSE (even though I’d qualify for the full version under the Personal Use license). I’ve been considering why it might be a better choice than VMware for businesses.