Bob Cringely points out the obvious reason that Windows and Linux are more popular than Macinoshes: Macs are too easy to use, so IT departments will not recommend Macs because it will put them out of a job.
Microsoft is one of the most evil entities on the face of the planet, and not just because they are crooks. It's much, much worse than that. Because of Microsoft an entire generation of people has grown up believing that operating system crashes and computer viruses are just part of the Way the World Is. Even today, with Linux and Mac OS X as proof that reliable virus-free software is possible, most people I know seem to be incapable of conceiving a world where Microsoft, system crashes, and anti-virus software are not an integral part of daily life. To my mind, people who defend Microsoft are not unlike the slaves who fought on the side of the South during the civil war. They toil in the fields (or the cubicles as the case may be) while Massa Bill over in the Big House pockets the fruits of their labor.
I feel sorry for them. It's not their fault.