I use My Computer primarily for the Microsoft Flight Simulator. I currently have Windows 8 , but would like to change it to Windows 7 , because Windows 7 is more compatible. I have Windows 7 on my shelve but can't remember if it has been used.If it has been used, then it's no good. Two questions ; First Is there an easy way to tell if it's good. Second, how difficult is it to change operating systems. I only have a basic knowledge of computers. My Computer is a HP. Thanks