@GreggBz
I thought it might be driver issues, hadn't thought of the security issues though.
I can't see other *nix solutions competing with OS X. OS X "just works", it has a nice user interface (IMO) and Apple is associated with ease of use. Linux, OTOH, is perceived (rightly or wrongly) as complicated, and can seem confusing to newcomers. The same goes for other *nix systems.
OS X might stand a chance in the consumer market, especially if it was pre-installed on PCs through some licensing deal with a major PC company. Admittedly this would cut into their hardware sales, but some people would still want Apple hardware (I for one think the current iMac is gorgeous, Apple definitely makes some of the more stylish PCs!)