I brought an old computer up through Win95->Win98->XP and at each step is was a hair-pulling experience to bring at least a few of the old programs forward, although others worked fine.
If you have a patient friend with a fairly new computer and an external usb to IDE docking station, you can try running some of those old .exe files directly from their file locations on your old hard drives without going through a formal installation procedure which would require having original installation discs. Just double click on the .exe files in File Explorer. You may get some to work, I don’t know if Cubase stuff would be among those, however. That definitely won’t work with any Mac or Linux system, even with Windows emulators. You can pick up relatively recent early generation i7 and i5 computers with legitimate Windows 7 or later installations for less than $200, Amazon has some refurbs. That’s what I would do in a budget conscious situation, assuming the old exe files prove able to run on such machines.
In any case, don’t put a Win98 or XP computer online, they are sitting ducks for hackers. Vista is almost as bad.