I've been a Mac guy since the late 80's. At that time a Mac was the only choice, there weren't any music applications for PC. Up until very recently the only serious (read: used by professionals) programs for audio and visual editing were Mac based. More PC programs began to emerge at the turn of the millennium, but professional editing programs and their associated plug-ins are VERY pricey, and having to upgrade cross-platform was correspondingly expensive, so professional facilities stuck with their Macs.
The birth of the internet meant that things had to be cross platform, so the Mac vs. PC debate has become virtually meaningless. Many softwares - like Pro Tools and Avid - are available for both Mac and PC, although there are still Mac or PC specific programs.
I think that what really has come out of the PC vs Mac debate is the realization that, whichever you choose, if you are doing serious visual or audio editing, your box should be a single purpose machine, meaning that you have a computer dedicated to audio or visual editing - no games, no internet, nothing.