Horses for courses.
You've opened up the can of worms me thinks. From my perspective I love both my PC and my Mac. I run the same programs on both (SX) and they both have stability issues.
It really does depend on what you expect to be doing with the computer.
The mac functions very well as standalone for music apps, and networks well with other macs. But my 2.4 gig p4 runs like a dream as well, and is used constantly for live work.
The biggest lesson you can take from this is.....if it aint broke, dont fix it. I presume that your PC is connected to the net? This IMHO is a mistake. All my music computers have their network components removed as much as possible, they all run SP1 with no updates, ever. And have yet to let me down in any major way.
I use the macs at work (eMACs) and i hate them, but a friend of mine has a G5 and it rocks! Expensive tho. If you want to spend money on a machine to create music you really do need to get a good soundcard, as this is probably the most important part of your setup, dont overlook it.
Software for the PC is more widely available than the mac, and if you use warez'd stuff constantly the PC is probably a better choice. MAC appz are infrequent and usually unreliable. Logic on the MAC is defo a good choice, SX for the PC - so it comes down to which sequencer you use.
Sorry for the ramble, hope you aren't confused too much!![]()