Just hooked up the external drive to the old "ME" pc and it can read the files.
I did try & rush things a bit by removing it too soon & got a message about "flushing" or something similar.
But re-connected it to "ME" pc and it seems to work as normal BUT when I connect it to the XP pc I am still told it is not formatted.
That is strange.
If all else fails I can copy files from the old pc through the network to the XP pc, but should that really be neccessary?