My dad did the upgrade to Windows 10 from Windows 7. It looks interesting but I like my Windows 7 setup. I don't want to mess it up. So, can I do a clean install of Windows 10 as an upgrade but keep Windows 7 on the same computer in a dual boot setting? That way I can try Windows 10 without anything getting messed up in Windows 7. Or do I have to buy a separate license for Windows 10 in order to have a Windows 7 and Windows 10 dual boot?