Legality of using a burned CD with a legal CD-Key? [closed]

I have a friend that keeps a collection of burned Windows CD's; 2000, XP, Vista which he uses to repair peoples computers with. Now he justifies this by saying he uses the CD-Key on their OEM sticker that came with their PC. As long as the installation validates the installation should be 100% legal. Is this true? I've always been under the impression you had to use the original CD/DVD that came with the computer.

It's the key that's the important thing, as long as each machine uses it's original key then you're legal. You can use the OEM key if it's available, or the key that came with the disc if they had installed a retail version of Windows. In the latter case you don't need to use the original disc as the burned installer is treated the same as the pressed disc.

NOTE: I'm not saying that you can reuse keys from other installations, as that would clearly be piracy. If you have a valid key then at some point in the past you (or the OEM) had an installation disk.

Your friend is incorrect.

The licensing terms for Windows Vista seem to suggest that the single allowed backup copy is permitted for use only for reinstallation which would forbid fresh installs:

BACKUP COPY. You may make one backup copy of the media. You may use it only to reinstall the software.

Arguably, this could be interpreted as leaving room to reinstall on other machines. This interpretation of Microsoft's intent is doubtful, based on their wording regarding Windows 7. The language at the Microsoft Store explicitly states that the Windows 7 media is to be used for the licensed computer only:

The license terms for Windows 7, once accepted, permit you to make one copy of the software as a back-up copy for reinstallation on the licensed computer.

Use of the definite article suggests it is illegal to use it on just any computer (ie., "the computer" vs "a computer").