To end this thread:

Yes, I have a whole HP partition which is for Restore purposes, but I
have no stomach for reinstalling years of finely tuned apps.

As for Add/Remove, there is no sign of anything in there related to
SP1/Sp2/Sp3.

I wanted SP1 to be able to run an older Visioneer scanner which the
manufacturer claims won't run on SP3. But for a decent price, Visioneer
is selling me a factory-refurbished and warranted more modern version,
of the old scanner. So for only a moderate cost, I hope I will be back
doing hi-res scans of 35mm slides again.

Thanks for all suggestions.