I just installed windows 10 from being on windows 7 from a usb. Everything works fine. I already had to set a drive letter for my secondary hard drive. I have 3 internal hard drives, and i cant access the other two that the os isnt installed on. You see... what i did was took a hard drive out of my other pc. Wiped it when i installed windows 10, and the other two still have my stuff on them. One of the other two has a working version of windows 7 and i don't know how i can claim it to be able to open and use my stuff. I am advanced at pc's and can do alot of things so throw it at me.