found new hardware redundancy
"Kill the found new hardware wizard by running services.msc and then turn off Shell hardware detection".

This appears to have resolved the annoying and unassailable pop-up wizard that has been flogging me on the old Big Beige Box ever since I plugged the 400GB IDE into the CD cable for the next 3 weeks.
Of course, it'll probably prevent me installing any new hardware on the old clunker, but that's not likely to happen.
I can't be bothered finding out why the Big beige Box suddenly doesn't want to recognise an IDE drive ....