I bought an educational version of Windows 7 Pro 64 bit to install on my Dell desktop. The hard drive had died so I put in a new hard drive and tried to install the OS with good results up until the point of putting in the product key. More than double checked accuracy, but still didn't get the key recognized. I went ahead and installed Linux just to see what would happen and it installed with no trouble. But I still need to get Windows on there. Any suggestions? I lost all my discs from the OS that came with the computer a few years ago.