I'm tired. I'm not gonna go into detail right now.
Mac has a better implementation of virtually anything that's available on PC, with one notable exception being gaming. If you really like playing the latest games, don't get a Mac, because most developers (but not all) release exclusively for PC.
Other than that, I can really not think of many important reasons for you to choose PC. It's inferior software, period. If you have an open mind and are willing to learn a new system (that's extremely easy to get used to), I can almost guarantee that you won't want to switch back. It'll also save you the headaches of having to get rid of whatever virus infestations you'll surely get at some point.
Don't even fall for the misunderstanding that Macs are more expensive than PCs.
EDIT: postscriptum: I'm a long-time MS-DOS and Windows user who started out with the very first version and ended with XP. I finally ditched it after working with Mac OS X at a graphic design studio. Now I've used Mac OS X exclusively for the last three years or so. I also use Linux, but you don't need us to tell you whether you should be interested in it.
Mac not very good for CAD
My brother is an architect who works in London and he has a mac and there are no decent sotfware for it. Everyone in the industry uses PC becuase microstation is the leading CAD software
But you know, you can get windows on mac now, so that's not really much of a problem.
If you have the money, go for mac and get both OSX and Windows as you can switch between the two so best of both worlds.
I might be wrong about this, but I have the impression that most people in the music recording industry use Macs. I'm assuming this is because recording and editing programs get better support and updates on Mac OS than on Windows, especially things like ProTools and whatnot. Macs probably have better compatibility with audio hardware too, maybe???
hmm I don't think there is much difference at all really. Plus, have you ever used pro tools? It's the most overhyped piece of garbage ever. It looks like a piece of shit from the mid 90s. It runs on both platforms though. I've read record labels will only record with studios that have pro tools so the studios HAVE to have it, but often may favour other DAWs.
The main disadvantage is that you can only use Logic on Mac and Logic is a fucking awesome DAW. Probably the best there is. Unfortanetley I don't have a mac, but they have them at uni and you can do some awesome shit with it, although there are some things I absolutely despise out it