Ok I guess I better chime in here.
I'm personally a big mac-head. I prefer the OS to Windows because I find it more intuitive and better laid out. That said, when switching to a mac for the first time many people think the opposite because they are so used to the paradigms that windows uses. There's always a learning curve when switching OSes, whether you're going from mac to windows, windows to mac, windows to linux, or whatever. I prefer how the filesystem is laid out on the macs, because I find it a lot easier to navigate through your hard drive. You rarely find files that are buried more than 11 directories deep on your HD, and anything that you're likely to need access to on a regular basis should only be a couple clicks away. Your applications are all in your Applications folder, your pictures can all go in your pictures folder, your music in your music folder, etc. Unless, of course, you want to put them somewhere else, which is no problem. You can also make "smart folders" that automatically gather files from anywhere on your hard drive based on whatever kind of search criteria you set for it. I've never liked the whole "start menu" idea personally, because to me it feels like windows is trying to hide the programs from you and only give you a little shortcut to it in the menu.
Sure, macs are a bit less customizable than PCs, both in terms of hardware and software. But again, a lot of people think that macs can't be upgraded or changed at all, and that's simply untrue. For some reason a lot of people seem to compare the upgradability of a custom-built PC box to that of the iMac, which is unfair. iMacs are made to be an all-in-one compact computer that is oriented towards the consumer market, and not a professional workstation (but that's not to say they're not good machines; they really are nice, powerful computers). Powermacs are much more upgradable (although admittedly still less so than a PC). You can't replace the motherboard, but there's plenty of space for extra drives, video cards, PCI cards, not to mention RAM of course (which you can upgrade in any machine), and
sometimes the CPU. Macs come out of the box as very good systems, especially since they started upgrading to the intel chips. That won't help you a lot down the road, when your computer is old and slow compared to what's out on the market now, but it certainly won't slow down any as it ages. My father up until just a few years ago used to use a Powermac 9600 from 1997 as his main computer for all the professional audio production he does for a local radio station. My point is: although macs aren't the most upgradable, in my opinion they remain great machines for a good long time.
This brings us to the issue of the new intel chips. Some people seem to be confused on this issue. Here's what's going on. For a long time Apple has used Motorola and IBM to manufacture chips for them. Chips such as the G4 and the G5 (motorola and IBM, respectively). When they G5 first came out, Apple promised that they would have 3Ghz chips in their powermacs within a year. However, IBM never delivered on this. Their G5 chips just couldn't handle it (mainly because of overheating issues). Apple also could find no way to fit a G5 chip into a laptop, which they really wanted to do. So they thought a bit, and made the decision to make the switch and use intel chips in upcoming machines. These intel chips are the same kinds of chips that Windows runs on, as opposed to the PPC chips like the G5. Now they have faster computers and can fit better processors into smaller computers like the Macbook and Mac Mini. But when it comes to software this means a few things. Primarily, software that was made for G4 / G5 chips won't work
natively on the new intel chips. Developers need to recompile their software to work at full speed on the new chips. But that doesn't mean that older software won't work at all on the new computers; it means that it will have to run though the OS's built-in emulation software called Rosetta. And from what I've heard, it does a pretty good job. It's not going to be as fast as a G5, but it's not going to be horrendously slow either. Why this information is especially important for photographers though is that Photoshop as of now has not been upgraded to work natively with the new chips. Adobe says that they will not release an intel-compatible version until they ship their next version, CS3, in the beginning of next year. But once it comes out, I'm sure it will be quite fast.
So far Apple has upgraded all of their machines with intel chips except for the Powermac and the XServe. Rumorists suspect that Apple will use either the new Core 2 Duo chips in them or some new Xeon processors intel is expected to announce soon in the machines. All the other machines are in their first version since the upgrades, and some people don't like to buy stuff right when it's released because of the possibility of hardware bugs that don't get worked out until later revisions. I've heard some people having issues with the MacBooks and MacBook Pros, but from what I've heard I think the iMacs are pretty stable. With the exception of the issue with Photoshop not having native Intel support yet, now would be a fine time to go with a new iMac. Unless you just don't click with the OS or you just feel like you
have to upgrade your motherboard I think you will be good with a mac.
Ok, I've been typing for a while, and I have no idea how long this post has gotten, so I'm going to stop here. I think I've said everything I wanted to say.
Also, I forgot to mention, that now that macs have intel chips in them, they are in fact capable of running windows natively as well. You can use either Apple's Boot Camp software or Parallels Desktop software to run Windows alongside Mac OS on your computer. So now when you buy a mac, you're not stuck to the OS if you really don't like it (but how could you not love it? ;-) )