I was a PC user for many years, but switched to Mac and I doubt I'll ever go back. With my PC, I was constantly experiencing issues when I would load new software and something else would stop working, or have to be disabled, or I'd have issues with drivers, or I'd get some arcane error message and have to search forums trying to find the solution. On top of that there was all the spyware and viruses.
This is not to say that Macs are perfect! They are a lot more expensive than PC's and, like many vendors, Apple has an annoying tendency to release something that works really well, then change it for the worse in a subsequent release for reasons that don't seem to be related to the user experience. Also, there is much less software available for Macs, since PC's are such a larger market. However, when I load new software on my Mac, it works right away without exception and the OS never crashes. On rare occassions, an individual app might crash, but then I had the same problem with Windows and since I upgraded my memory, this almost never happens.
To speak more specifically about music production on a Mac, Macs come with Garageband - a very user-friendly tool which is sufficient for many people's needs. I decided to upgrade to Logic Express 9, as it includes advanced features, including a virtual drum machine (Ultrabeat). I haven't tried Logic Pro 10 yet, but Apple's strategy was to make it more similar to the interface of Garageband, so the transition from one program to the other will be easier going forward.
Not trying to sound like a paid shill, others would of course disagree with me. But having used both systems, Macs work better for me.