My pc does not have a disk drive, nor will i install one. Can someone give links where I can buy windows 8 or 7, preferably cheaper one. ( they're going to give everyone a free upgrade to windows 10 anyway) And it has to be digital. I have to be able to install it with a usb. realy all i need is a windows 8.1 pro product key. or just a windows product key in general.