Zitat
An upgrade of the motherboard is considered to result in a "new personal computer." Microsoft OEM operating system software cannot be transferred from one computer to another. Therefore, if the motherboard is upgraded or replaced for reasons other than a defect then a new computer has been created, the original license expires, and a new full operating system license (not upgrade) is required. This is true even if the computer is covered under Software Assurance or other Volume License programs.
Sprich -> Neues Motherboard bedeutet neue Windows Lizenz
Quelle: http://www.microsoft.../oslicense.mspx