This is my first time installing Windows so I really don't know what I'm doing. I still have Windows 8.1 installed on my HDD and I can run it (I have only one drive). Should I still have it installed? My friend told me to format my drive but I don't know how or if I should. Also, it came in a box and it had a USB drive inside. The instructions say to just boot from the drive right away. I may have done it wrong.