@John Savard Re: natural monopoly
Natural monopolies only occur when there is a _physical_ reason for the monopoly - not market reasaons. An example of a natural monopoly would be power distribution, or even better would be a mining facility. Extremely high capital costs or there's only one (or only several) place(s) to get the material.
However, being a perceived monopoly (a la Microsoft) could be a determining factor for government intervention to to monopolistic practices. In MS case, it's really a shame that politics got involved and they didn't get more intervention because of their proven monopolistic practices (as proven by the courts in MS v. Word Perfect)
As far as name recognition, you have a point. In the case of Linux, it's taken off despite the lack of name recognition for Linux itself, but Red Hat seems to have taken off in several sectors (like server space) despite not having the name recognition.