My Daughter is doing a Music composition course. As modern music is now composed on a computer, the educational institution concerned uses a program called Logic Pro http://www.apple.com/logicpro/. It only runs on Apple computers because, as I understand it Apple own Logic.
As she owns a number of PC's my Daughter has tried several PC based music composition programs and discovered they are either to simplistic, compared to Logic, or are so complicated that she finds it very difficult to use them. The latter is Cakewalk Sonar http://www.cakewalk.com/products/sonar/ which apparently is more designed to be used by sound engineers than musicians.
My Daughter spends her days at her music school using Logic on a Mac and then comes home and tries to do the same thing on her PC using Sonar. I am told, by her, that in addition to Sonar being extremely difficult to learn it often does the equivalent to logic in a completely different way. Additionally, even though she has worked out how to take some of the files she does at school on Logic and get then in to Sonar, the result ends up sounding completely different. The reason she has been give for this is because their are musical instrument sounds that exist in Logic in the form of Midi files that at not equivalent, in Sonar.
It would appear that these instrument sounds that end up being stored and played in Midi files are a bit like fonts in a word processor. If a word processing file that uses a particular font on one computer is read on another computer with exactly the same program it may not appear the same if the fonts concerned are not on the second computer.
To complicate things even more with music compositions you can have affects placed on each musical instrument and they are different and implemented in different ways with Logic compared to Sonar.
It would appear that the only way my daughter can continue with what she is learning in her music course is to go out and purchase an apple Mac.