My suggestion would be to try a C64 emulator and some disk images. The "OS" is essentially ancient MS basic, some disk-based GUIs exist (but pretty slow on unaccelerated machines).
I have mad respect for guys like red who build kick-ass projects based on C= 8-bit stuff, and while I still fire up my 128 on rare occasion, I doubt many non-nostalgics would develop lasting interest. (Maybe I'll be proven wrong.
