A desktop that I had which was used for work recently would not activate because it required connectivity to the companies KMS server which I would connect to via VPN to complete but since I no longer work there that is out of the question. Since the Vista OS was an enterprise version I had no way to purchase a license for it. I did however have a Vista Business license that is legit so I wanted to migrate to it from the version of Vista Enterprise.
First make sure that everything near and dear is backed up in case something goes screwy.
Before inserting the Windows Vista CD
Go to, Start, Run: and type: regedit.exe
Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
Change the key : ProductName from “Windows Vista ™ Enterprise” to “Windows Vista ™ Business”
Change the key: EditionID from “Enterprise” to “Business”
Do not restart
Now insert Windows Vista CD and start upgrading (the option Upgrade will not be graded out anymore)
A copy of program/drivers had to be reinstalled but much easier solution for me then reinstalling everything which is usually a week long process it seems like now.