Ok, so I'm building a new system and bought windows 8.1 and after thinking about it I'm not sure about getting everything tested and running in 8.1. Can I just throw in my old windows 7 disc and purchase a new key after the install? The current Key is being used on my old system that I'm keeping for now. Going to leave the package sealed and return the 8.1 anyway (mistake on my part). Got all my parts and wanting to get it running this weekend. This would be easier than downloading and creating an ISO for me, I haven't built anything for quite awhile. Don't know how smooth this will go.