I’m reading Paul Thurrott from windowsitpro.com latest email newsletter on “Have Fun Purchasing Vista” within which he makes an interesting comment:
“Businesses, by the way, qualify for volume licensing. There are numerous prices, and it’s always cheaper if Microsoft can convince you to buy Vista right away. Volume-license customers qualify for their own versions of Vista Home Basic, Vista Home Premium, Vista Business, Vista Enterprise, and Vista Ultimate. Vista Enterprise has one almost assuredly useless but unique feature: You can install as many as four more copies of Vista Enterprise on virtual machines. There’s just one hitch: All the copies have to be running on the same PC that’s running the first Vista version you bought.
I’m not sure how this would apply to ESX considering is not a PC, and we regularly move VMs around using ESX.