OK. here is my story: I have 5 computer at moment, which is 2 for work, 2 for home and one for kids. their are all PCs,and use different OS. 3 of those PCs have ESS4 which is 3yr 3pc key. which still have 2yrs to go. I need 2 more licenses, anyway. recently I bought a new Macbook Pro.I love it, but I still need use window OS for work. So I have a solution from Apple is either use Bootcamp to dual boot or use virtualisation apps like I used on PC. option are VM Fusion 3 or Parallels Desktop 5.0. VM Fusion 3 have good support for OS other than windows and Parallels is good for speed and gaming. So I bought VM fushion and going to try Parallels. also I have the Bootcamp tri boot(Mac OS X/XP/Win7) as well. 1. For additional 2 PC can I add 2licenses to my old 3yr3pc licenses or I need new licenses? 2. I know if I build a new window virtual machine on Mac I need new ESS 4 license for it.but if I clone one of my PC to a virtual machine do I still need a new license for it or just use the one I used on that PC? 3. Do I need individual license for tri-boot OS windows XP and win7 on the Mac or they can share one? 4. If I have a PC have XP Vista and win7 3OSs on it, do I need 3 licenses or they can share one? Great thanks to anyone can answer those questions.