Hi as well.

I use both Mac OS X and Windows XP, and I can say that for things such as
file management, and interface consistency, Macs are more pleasant to use.
The software and hardware simply look better, and feel better. Everything
seems to be friendlier, more logical and more consistent.

I don't know much about music composition software, but my understanding is
that the majority of musicians use Macs, so again, who are you trying to be
compatible with? Musicians or the rest of the world? I do know for a fact
that the majority of visual artitsts (my field) use Macs. Also, Apple now
owns Logic, "the most widely used program of its kind in professional music
production. It elegantly combines composition, notaion, and audio production
facilities in one comprehensive product." See link:
http://www.apple.com/software/pro/logic/ Many scientists also prefer Macs
because of its UNIX underpinnings, though how relevant that is for you, I
don't know.

But really, it all depends on what you want to do. Despite what David Chien
posted, you can use a Mac and still be compatible with Windows users. Most
file formats are cross-platform, and a Mac can access a Windows network or
hard drive with very little problems, and no additional hardware. On the
other hand, a Windows machine cannot mount a Mac-formatted hard drive on its
own. Just remember, you may find it harder to get official support among
College IT staff. You have to know how to do some things yourself, or find a
Mac expert who'll help you, or find an open-minded IT person to figure it
out on the Mac for you (because it really isn't that hard, most of the
time.)

Microsoft Office X for the Mac is very good, and can open any Windows Office
document. Its only major glitch is lack of support for long filenames.

Also, you can get a Powerbook with resolutions up to 1440 X 900, despite
what David posted, again. But that's the 17" model, and it's very expensive.
The 12" model is compact, and a work of art. Its only major shortcoming is a
lack of a PC Card slot. So maybe that model is not going to work for you
unless there's some sort of Ethernet or Firewire solution... The 15" model
is a good compromise between the two, but it is an older design that is
going to be replaced soon, I expect.

Your choice basically boils down to the PowerBook G4 12", 15" or 17", or the
vast world of Windows laptops. If you decide to go with Windows, I would
stick to the newer Pentium-M machines (not to be confused with Pentium-4 M.
Stupid Intel branding...) The Compaq x1000 would be near the top of my list
as well. It's big, fast, capable, with lots of pixels, great battery life,
and a good price. For a nice smaller machine, look at the Fujitsu P5000.
It's an amazing piece of engineering miniaturization.

If you watch DIVX or XVID, go with Windows. If you play games, go with
Windows. Macs are woefully undersupported in these two areas. But for almost
everything else, you have pretty good software choices (though not as wide
as with Windows) and won't suffer the compatibility blues too much.

BTW, I know this has nothing to do with music composition, but iTunes for
the Mac is a fantastic music jukebox app. Nothing I've seen in Windows,
Muscimatch, Winamp, Windows Media Player, comes even close to iTunes in
terms of its many organizational capabilities.

But if you value attention to detail, and want your computer hardware and
software to look like it belongs in an art gallery or the set of a science
fiction movie, Macs are nice. But it's not just appearance. It's
human-interface design as well. Don't get me wrong. Windows XP is great,
with lots of very powerful features, some of which are not on Mac OS X. You
can do anything on a Windows machine that you can do on a Mac (well, except
maybe for iTunes...) It's just that you do it with less elegance and
consistency.

Now, having said all that, different people react to different things in
different ways. The best thing to do is to find a friend who owns a Mac
running OS X 10.2, and someone who owns a Windows XP machine, and ask them
to show you around. Go to a computer store and play with the models that
interest you. Go to the company websites.
http://www.apple.com/ http://www.microsoft.com/windows/default.mspx
http://www.fujitsupc.com/ http://www.hp.com/

That's about it. I hope this helps.