From my experience since it is an upgrade, you would not only have to have the original Windows Vista disk that included his 25 digit product key, but also have the Windows 7 upgrade disk and the 17 digit product key.
That way you can install Windows Vista first, and then after the computer has installed the original operating system that came with it in the first place, put the Windows 7 upgrade disk in.
After doing what I said you should have Windows 7 back up and running on his machine.
You cannot just plop in the Windows 7 upgrade disk because it does not contain the full operating system. It only contains the upgrade version. The upgrade version will only run once you have installed the original operating system on it.
That way you can install Windows Vista first, and then after the computer has installed the original operating system that came with it in the first place, put the Windows 7 upgrade disk in.
After doing what I said you should have Windows 7 back up and running on his machine.
You cannot just plop in the Windows 7 upgrade disk because it does not contain the full operating system. It only contains the upgrade version. The upgrade version will only run once you have installed the original operating system on it.