Hello, just a few observations from me, since a have a few T400 motherboards (in various states): Once, before having raspberry "programmer" I've just exchange flash chips between 2 motherboards, by de-soldering and re-soldering them - it worked. There are also flash chips with original T400 bios on sale - what about this? Lenovo is known for problems with bios updates (check: "T400/T500 slow boot after bios update" in google), so I suppose these chips might be useful. The problem that comes to my mind is MAC address that is stored in flash - we know how to change it with coreboot, but I'm not sure if on original bios also. If the MAC is stored in the same place in coreboot and bios then it would be possible to change it.
Peter: Is that really the case with old T400? The MAC might be a problem, but what else? Maybe there are some things that I'm aware off, and while motherboard looks ok in reality it is not.
Since all methods are rather complicated (and I don't have original bios anyway), maybe the easiest would be to read flash chip with original bios (from any unused mainboard) then just flash it to the "right one", then follow with normal windows bios update - what do You think? Michael Widlok