My brand new digitizing workflow using a 25 year old film scanner

I'm not surprised at all about having to use an old computer to get this thing to work. This will become the norm with scanners unless someone with more money than sense decides to enter the market.

Nearly all of the good consumer-grade scanners (i.e. those that use CCD sensors) are out of production and use software that is no longer maintained. The main market for scanners has become receipts, which has lead to a switch to cheap CIS sensors since quality no longer matters.

Outside of expensive specialized scanners, the Epson V600 is pretty much the only scanner in production still using a CCD sensor and it came out in 2009. It has nearly doubled in price over its lifetime to $350 due to lack of competition and I presume inflation. It is the de facto scanner used in the trading card world because of the output quality and ability to create templates within the software (I 3D printed my own brackets to be able to scan/crop 4 cards at a time perfectly every time). But last I checked MacOS support is pretty much gone and even Windows is barely tolerable. Its days are probably numbered, too.

I bought a V800 about 10 years ago for film scanning and it worked with modern computers. The quality was quite good as well; I wet-mounted my negatives and had pretty much no complaints with the quality. Speed was not amazing, of course.

I ended up with a flatbed and not a film scanner because I wanted to scan 4x5 negatives.

If I were being rational, I'd just get an A7R or Fuji's medium format DSLR for 90% of my photos and have 4x5" and larger negatives professionally scanned. For proofing, I always found taking a picture of the negative on a lightbox with my phone and inverting to be adequate. If you like the photo in that form, then you'll like the professional scan.

Well, from my experience of going both seriously digital and seriously darkroom, i'd keep the two apart. Get a lovely 5x4 enlarger (or join a darkroom where one is available) and you'll enjoy making B&W prints from those negatives much more than you'll enjoy scanning them and looking at them on a screen.