Just to tie off this thread...
I did finally get the MFC upgraded by using the oldest interface in the house (a dusty old eMagic MT-4) and an ancient Windows ME USB 1.1 laptop that a cat had thrown up on. Worked first time, so I have to thank everyone here who contributed thought/ideas/sympathy, and also Snookie (the cat) for her contribution as well.
I guess the lesson here is to use the funkiest, junkiest, stuff you have to upgrade that expensive new stuff. Sheesh.
TT