I was a Mac guy for a long long time, got a Windows box in 95, sold
my last Mac about 98. I'm a software engineer and have written lots
of application and graphics software for many versions of both
platforms' OS software. The main reason for my transition was
financial; it was getting hard to find Mac programming jobs. But
once my initial predjudices were laid to rest, I found I liked
Windows well enough, and didn't see much reason to cotinue owning
Macs.
Mac-heads will tell you things like "The Mac was designed from the
ground up for graphics, and Windows wasn't", but this is about as
up-to-date as saying "Macs now have color!" The truth is you can do
anything you want with both, there is nothing offered on the Mac
you can't get on Windows (except perhaps Final Cut Pro, a
video-editing suite that is supposed to be the bomb, but I haven't
used that myself). The Mac is probably easier for a rank newbie,
but Windows machines are still much cheaper for equivalent power
('ware marketing!). In my opinion Windows is much better for power
users, UNLESS you are an accomplished linux or other unix user, in
which case Mac OS X is probably a better choice. Both Win2k/XP and
Mac OSX are modern, stable, efficient operating systems. Mac OS9
and earlier are very primitive operating systems in many ways, and
tend to crash a lot. Ditto Windows 95/98/ME.
Now, which one you want really boils down to wheter you like to do
things the way Steve (Jobs) likes to do them. If you like this way,
then you'll like using the current Macs. They will in fact cost you
more, but they're pretty to look at and fairly complete packages.
If you don't like the way Steve works, you may not like using the
current Macs.
Windows does now and likely always will have much more software
available for it. A lot of the extra choices aren't very good, but
you are much more likely to find a tool for the task you have in
mind. Windows also enjoys support from just about every
manufacturer of other computer-y device made, from digital cameras
to MP3 players, printers, etc. With very rare exceptions, you can
use all these items with your PC. Only a few of these also support
use on a Mac. A Mac enthusiast will likely argue you wouldn't want
any of the devices that don't support the Mac because they're
inferior, and this is sometimes true, but only sometimes. The one
device I can think of that only works with a mac is the iPod, which
is a very nifty well-done device but hardly the only hd-based MP3
player (certainly the priciest though).
As for things like performance; I think Wintel boxes will always
have an edge, particularly when you do a price/performance
breakdown. Millions of Intel chips vs. thousands of PowerPC chips
makes this so. Both platforms offer choices that give you loads of
power; my P4 1.7 handles the 6 megapixel images from my D60 quite
nicely. I'll upgrade when this ceases to be true (and it won't cost
me much).
Hope that helps; there is a lot of religion around this question,
so be prepared for that.