Slightly less embarrassed update.
Having checked through some 12 HDs trying to locate the needed one, I eventually started from scratch and loaded XP onto each one on the subject machine until, at the seventh go, the disk offered me XP already loaded ... Whoopee!!
That was the one and the files were all there. Soooooooo ... attaching both belt and braces, I copied everything I could find onto TWO different disks and they will, in turn, be copied onto the new machine. However, there remains the perrenial problem of Emails. They're all there but I can find no simple method of transferring them onto the new machine. Tried selecting all and copying to MS Outlook but that ignored everything but the first one. I seem to recall that this has been covered here previously but cannot find a reference. Can anyone offer a simpleton's approach, please?
TIA