I'm building a pc soon and would like to use windows 7 os on it so i went to an old acer aspire one netbook i had and found the windows 7 product key on the bottom and tried to download it from microsoft's windows 7 reinstall page and get this error message: The product key you entered appears to be for software pre-installed by the device manufacturer. Please contact the device manufacturer for software recovery options. I have not a clue what this means and i don't know how to solve it.