I did not ask for an excuse on why you were attempting to do it -
just letting you know that according to the strict guidelines of
the OEM End-User License Agreement - you may not transfer that
license/copy of Windows XP from one machine to another under any
circumstances.
As for the technicals of how to fix a ghosted system after going
from one hardware platform to another - I gave you that - a repair
installation using your original Windows XP installation media.
Realizing you may have never done this before:
How to Perform a Windows XP Repair Install
http://www.michaelstevenstech.com/XPrepairinstall.htm
How to perform an in-place upgrade (reinstallation) of Windows
XP
http://support.microsoft.com/kb/315341
What specific application could possibly be 'so complicated'?
Managing several thousand machines with multiple dozens of
applications on them is what many of the people here (who choose
to help others) do... Perhaps if you asked for assistance - we
could give you a simpler solution for this application.