I bought a Dell desktop new with WIN 8.1 on it about 6 mos ago. I downloaded WIN10 a couple months ago and it works fine. I don't like WIN10 or WIN8 for that matter. I called DELL support and they confirmed I can load WIN7 and my PC will support it along with associated drivers. Can I still buy a new registrable WIN7 64 BIT OS disc? If so where would you recommend?