One of the improvements Microsoft is making to Activation 3.0 for newly built machines that come preloaded with Windows 8, you won't have a COA (Certificate of Authenticity) sticker attached to the machine anymore. Instead, this will be embedded in the BIOS. This will avoid product keys from being compromised and OEMs will buy what they need.
The OEM license is actually non-transferable to another PC. When you buy a PC preinstalled with Windows, that version of Windows is only licensed for that PC and cannot be transferred to a new PC. The transfer of the license must accompany the PC it was licensed for. If the customer were able to get that machine fixed, they would simply need to call customer support to re-activate if there were changes big enough to merit PC reset or system recovery unusable.