Notice I didn't say that MS caused open source, rather it turned what was a small group of people into an major movement. A large percentage of the people using Linux at home today did not go with Linux because it's Unix or because it works better. They went to Linux because it's not MS, they went with Open Source because it is the opposite of the practices of MS.
The Open Source movement may have succeeded without MS, but MS certainly had a hand in driving people to it.
Jay