Im building my dad a pc, he has windows xp on a disk but he wants to use Auto CAD so he needs a newer OS like windows 8.1. He doesnt want to spend 100 bucks on windows so i told him to get a key from G2A but it doesnt come with an installer. I followed this link to get windows 8 without a cd but it says that you need to be running windows 7 or vista to upgrade but i need to install windows for the first time. Would the only option be to get a disk or can i use that installer if i dont have an os or can i install windows xp and do it from there. I noticed that it was not an ISO instead its an exe file.