[Coda]

No, that's the thing. You DIDN'T buy a copy of the OS with the system. You bought a system which had an OEM license for Windows associated with it. The license agreement you accepted when you opened the box containing the computer said it was only valid on that specific machine.

There ARE bundled keys that are semi-portable. If you're installing the key on a computer from the same manufacturer with similar enough hardware configuration, the key won't know that it's not being used on the same machine. For some manufacturers the keys may even be portable across all laptops or all desktops or possibly all computers made by the same company. And for PARTICULARLY small manufacturers, they may be using System Builder's licenses instead of OEM licenses, which can work on any hardware. (It's still technically against the license agreement to move them to different computers if you don't buy a full version of Windows yourself, but the technological enforcement can't tell.)

Regardless of the license type, though, even if you succeed in INSTALLING Windows, it might throw errors on ACTIVATION if the key was used on another computer in the past.

It's also possible I was wrong about Vista or that the enforcement on Vista wasn't as picky. But I know it's 100% true about Windows 7 because I ran into that problem myself a couple months ago because I was trying to salvage a failed laptop for a friend and he didn't have a recovery USB -- but I have one, so I used it. The installer was happy to go on with the key on the bottom of the laptop, but Windows started complaining later about activation.