Windows Vista OEM cert can be used in Windows 7 has been explained in Windows 7 forum.
The SLIC 2.1 can be modded into BIOS physically (hardmod or biosmod) or been emulated or simulated during Windows boots up (softmod). Various SLIC 2.1 BIN has been retrieved from various notebook computer that shipped with new SLIC 2.1 in BIOS to support the free Windows 7 Upgrade Option from Windows Vista.
The extracted Windows 7 Ultimate OEM-SLP product key, 22TKD-F8XX6-YG69F-9M66D-PMJBM, can be used to activate installed Windows 7 Ultimate system, which BIOS has a valid OEM SLIC 2.1, and corresponding OEM cert, even if it’s OEM cert meant for Windows Vista.Best news is that, the product key appears to be a master OEM-SLP product key for Windows 7 Ultimate, which able to activate many OEM brands, such as HP, Dell, MSI and Lenovo.

Use the following commands to convert to OEM version:
slmgr.vbs -ilc OEM.XRM-MS (where OEM.XRM-MS is a valid OEM cert matching with SLIC 2.1 in BIOS)
slmgr -ipk 22TKD-F8XX6-YG69F-9M66D-PMJBM
Both 32-bit and 64-bit (x86 and x64) Windows 7 Ultimate system should and can be activated immediately.
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