[rbanffy]

I would point to Ataris, Amigas, Transputers, RISC workstations, Lisp Machines, Xerox Star, Connection Machines, supercomputers, ... Not to mention the software that would be developed today if we weren't stuck with glorified 8080s running 60's OSs (Linux is Unix and NT is VMS)...

[binomial]

It is not unlikely that many of those would end up as failed endeavors whether or not MS existed. We can only speculate though.