I am trying to decide whether to have Ubuntu as my main operating system and then create virtual machines for my other Windows OSes (XP, Win7 & 8). Or whether I should run Windows as my main OS and then the others, including Ubuntu as a VM. I need all these OSes so I troubleshoot problems for clients. What are the pros and cons of each approach? And if it were you what would you do, and the main reason(s) why? Thanks you for your input.