A friend of mine has a used laptop with a formatted hard drive. The laptop originally came with Windows 7 Home Premium. The laptop has a Product Key sticker for Windows 7 Home Premium. No installation media came with the laptop.
He also has a DVD for Windows 7 Professional, apparently for installation with a new PC, that he bought off of e-bay for $20 (no Product Key came with it).
We were able to install Windows 7 Professional, but the Product Key doesn't work because it was generated for Windows 7 Home Premium, not for Windows 7 Professional.
The Windows 7 Professional DVD is, indeed, from Microsoft.
Can anything be done?