Do you have a CD from the PC manufacturer handy? Check on there to see if it has the installation files. Unfortunately this is an area where PC manufacturers have failed. Many times you do not have the installation files readily available to you because they are compacted into an image file for the system. Technically you can borrow someone else's ME CD and use that as your proof. You have a legal right to use the software, the license is separate from the actual software so it doesn't matter if you are using their cd or yours.