if i remember correctly, the problem is that apple doesn't release details for the connection between the bsd operating system and the aqua user interface, with the result that it's not as easy as i could be to write software for it, so basically, they're shooting themselves in the foot a bit there (of course, it still is a lot easier to write (or port) software for os x than it is to write software to do certain things in windows)
celeron processors (or intel in general) is worth looking into, because intel is quite open to the linux community, which is the future of computing.