If I could find a copy of NeXT's operating system, NeXTStep, would it be possible to run it in something like Parallels on a Mac? This Wikipedia page says that it ran on Intex x86.
Looks like you should be able to get it to run on VMware Fusion
Proof it can be done: http://www.youtube.com/watch?v=T9CfzpYt2Uc
Sources to get it to work: