not a mac fan either
but i have had the oppertunity to take an old G4 powerpc apart, and I have to agree with your comments.
Apple pc's are very well designed and tidy inside, with dedicated cable runs, ducting etc and other cool features.
there is one thing that puzzles me though.
the mac that I took apart was 10 years old. there were a few features inside that I would have expected to start seeing in normal desktop cases by now - one of them is a wireless antenna that runs round the outside of the case on both sides, and (i think) uses the actual case itself as an antenna. this cable ended in a standard fit connector, placed on the inside of the case in a convenient spot (i assume where you would put the airport card extension).
Now unless apple has a patent on all of this (which may be the case I admit) why, to the best of my knowledge, hasn't anyone else done that?