<<I had an extra Gateway E-4000 lying around, so I took her drive out and put it in that. Booted and got the BSOD>>
That's typical, I would say. A hard drive from System A...has different drivers and settings...than would pertain to System B.
Changing a Motherboard or Moving Hard Drive - http://www.michaelstevenstech.com/moving_xp.html
<<...so I popped in XP Pro CD and ran a repair. I got through all the file copies and got the error: "Setup cannot set the required Windows XP configutation information.>>
Well...if XP Pro was not installed on the hard drive...that makes sense to me. Additionally...if System A had any partitions created (recovery/restore) by the manufacturer...that might throw any repair efforts off. Lastly...if the XP Pro CD was not a MS Genuine XP CD, but a CD issued by some other manufacturer of systems...the CD may only be appropriate for the system it came with.http://kadaitcha.cx/cannot_install.html
, you have already read the MS KB for the error you received.
I will only add that...if the SP contained on the CD you attempted to use...did not match the SP existing on the system...I would not expect success.
<<I took an extra hard disk and installed XP from scratch in that machine no problem.>>
What machine is that, please? You've mentioned bad caps in one and a spare that you have. Which system was the drive in when you did this clean install?
It's not clear to me what system you are working on after you make the above statement.
You mention a Toshiba hard drive...does that mean that the system with the bad caps is a Toshiba?
Manufacturer and model for the relative's system?