I would love to simply stick my old HD into the case, but it would violate the warranty on this (newish) machine. For various reasons, I'd rather not break this warranty.
Here is what I will attempt:
1. Erase everything I have done in the internal partition thus far. Keep the external HD unplugged.
2. Image (not clone - I understand that the imaging process will not erase my other data) with Macrium the contents of my source drive onto the partition in the Internal, via Adapter. (I don't seem to have access to any Acronis software; I used the cloning software that came with the Adapter previously).
3. Unpack the image onto this partition, which I have changed from logical to primary, on my Windows 7 internal HD.
4. Use Paragon to feed the f6flpy drivers
from theog's link to XP.
5. Erase the old entries from EasyBCD, and follow the procedure to create an XP entry again.
6. Reboot the machine.
Hopefully it will work.