I have been playing around with VMware’s Esxi Server 4.1 on a spare server for a few days now so far what I have to say is..I LOVE IT. I used to use Oracles VM Virtual Box for the longest time and I was happy till I set up ESXI. One few things that I have been able to do is run multiple servers at once now. Before on my desktop I would run 1 at a time. Now I have a pretty beefy desktop (AMD Phenom 2.1GHz x 3 4GB Ram 500GB HD) but I would have to many things open at once and make things super slow. With Esxi I have about 3 running at any one time and can switch from one to another easily and my desktops performance remains unaffected. I have yet to find anything negative to say about ESXI. It was very easy to install and its free. What more can I say. Its great!