[ltp] New life for old IBM Warhorses?

[portsample]

Last year I did two things that got me thinking differently about 
laptops, 

1) My wife's T21 developed a problem where 10 minutes or so after
bootup, it would abruptly lock-up with no consistent initiator between
events. I ended up, (after swapping out hard drives, memory etc),
deciding that the problem was related to the motherboard. So before
ordering a new T21 motherboard, I decided to remove and then reinstall
the old motherboard to confirm that I was capable of performing this
kind of surgery. I did this, as well as removing and reseating the
Pentium3 processor on the motherboard. Amazingly, doing this was enough
to correct the problem: no new motherboard was required: the machine is 
still running flawlessly.

2) I pulled the processor, motherboard and other assorted obsolete
innards from my old (circa 1997) Quantex Pentium 2 desktop computer and
replaced these with a new ASUS board, 64-bit AMD Athlon processor, 
SATA HDs, a gig of RAM, a new power supply, and a RW-DVD drive.
Whoa. Now this "old warhorse" is the fastest machine in the office.

This brings me to the point of my posting: what are the standards for
motherboards and hardware in IBM laptops? There are several
manufacturers of laptop motherboards that will take the portable version 
of the 64-bit AMD Athlon: is there any possibility of swapping one of 
these into a classic Thinkpad housing? Obviously there are power, video, 
heat, and a host of peripheral geometry issues that in all likelihood
are show stoppers to producing any kind of a useful end product
without major tweakage and reengineering. Is anyone here aware of
hardware modifications such as this that have been done to Thinkpads or other
laptops? Does anyone know if this is even remotely possible?

Thanks.

Glenn