|I understand completely all the steps you took. Never the less, changing the jumpers was an exercise in futility.|
Anyway, you already had WinXP running on another hard drive?
Have you tried booting with ONLY the hard drive in question jumpered and cabled properly. If you have and you still have the same problem then you may actually have a true coincidence on your hands.
At that point I would suggest trying the drive on a second IDE channel, if one is available. If not, try running ONLY the optical drive on that channel and try booting from it. That will eliminate any IDE controller issues.
The fact of the matter is that no matter what is on a hard drive you should be able to POST. If you actually can't then you have a hardware issue.
I am still not convinced of that. Have you tried getting into the BIOS as soon as you start up?