the idea is that Apple's PC's are more utilitarian than IBM PC's.
windows is just more versitile than mac os-x.
apple wants to make sure everything works and fits together, and in the fast paced world of computers that doesnt happen-- perfecting things like there "i"series takes time and money.
microsoft just doesnt give a damn, they make a system and the it is left up to the developers to make sure their stuff works correctly.
in a way microsoft's ideals are self-suffcient-- if a windows application sucks it won't continue to sell, by the time a product hits the mass market or has time to release a new version most of the crap is weeded out and survival of the fittest takes over.
apple's ideals revolve around a perfect world where everyone just wants to make movies, surf the web, edit photos, and listen to music with proprietary software and versions.