We have a .VHD of a Windows 7 installation that was just converted from a physical machine. We copy this to our local hard drive, and then load this .VHD into Virtualbox and run the Windows 7 VM from our desktop in a window. How can I make it so that this can be used by 3 or more people at once without Windows asking for activation?(in the VM window)
To legally use it this way you would need to get a license for each of the extra windows installations. After you boot the VM go to [my computer], right click, select properties.
You will get this screen:
Click on "Change product key" and enter the new, legal, non OEM key.
If you want to make this a generic setup, start a copy of your 'Master VM' and run sysprep. That will remove the old key and make windows ask for the new key at first boot.