Microsoft FQC-00130 Quick Reference Guide - Page 22

Each of these conditions must be met in order for a base PC to be eligible for an upgrade licence: Software under the qualifying operating systems licence must already be installed on the device that will be assigned the Volume Licensing upgrade. The chart on the next page shows pre-installed OEM versions that are eligible for upgrade. You must remove the existing qualifying operating system from the device in order to deploy the Volume Licensing upgrade licence unless the PC is covered by Software Assurance. Customers who wish to install or run more than one licensed operating system at one time (including the qualifying operating system), may either: Acquire Software Assurance for their Volume Licensing upgrade licence Purchase full Windows 7 licences separately 22 - Quick Reference Guide