Alien You dont understand so I will explain.
The composition of the music never changed it was always the same music for all versions but the quality and the arrangement of the Amiga and the Mac was down to the hardware and how the hardware made the music sound. Which is the reason why pc version differs a great deal from the Amiga and the Mac version. The hardware for the pc version was more advanced and arranged the sound of the music differently.
The hardware handles the music for your games imagine it as an orchestra in your computer the better the computer hardware the better the orchestra.
Cool website buy the way try these 2 their also very good.
Video games music more great music and some great links
http://www.ocremix.org/
Game endings excelent website.
http://www.gamerevolution.com/goodie/endings