Is downloading Windows 95 and running it just because I'm curious about it legal?
- Purpose and character of the use: it's noncommercial, and I am doing it to learn about the software, but I'm not sure it's really "educational" because there is little or no practical value anymore in knowing how to use Windows 95.
- Nature of the copyrighted work: It is certainly not just a fact or idea, and I don't think it's substantially beneficial to the public for it to be in the public domain (although a case could be made that it is, because it is bringing exactly zero benefit to Microsoft and would have at least some benefit to others if it was in the public domain)
- Amount and substantiality: I would be using the entire OS.
- Effect upon work's value: None, Microsoft doesn't sell Windows 95 anymore and it could not reasonably be considered a substitute for modern Windows versions.
One of the four considerations does indicate fair use, one indicates non-fair use, and two are questionable.