My main workstation is like that! Now 10 y.o., it's about to be updated with a new motherboard, CPU, graphics, 16-32 GB RAM, plus an SSD. The main HDDs (3TB + 2TB) will migrate. New OS will be Win7 Pro 64 bit.

Then maybe 100 or so programs to migrate!

When I say 'updated', I mean that I have 6 other cases that are all but identical - 5 waiting for upgrades of one description or another. All will gain extra RAM, SSD at the minimum.

As you say, a bloody nightmare! I start by printing out a list of programs to be re-installed for each box ...
Since I have been doing this kind of work for a very long time, it's not quite as frightening for me as it is for some! But I'm getting older, and sillier ... .