Well, here are my reasons:
1.) I work in IT. My computer, therefore, has to be up and available *all the time*, I can't afford to be without it. Since I'm so closely tied to it, I ran my Windows XP install lean and slim - and because I put so much effort into keeping it happy, my WinXP has been just as rock-solid as anything else out there (including, in my opinion, OSX). However, I got real tired of the rather large amount of upkeep I had to do with my Windows system - I realise I'll have to do some for my Powerbook, I don't envision it being anywhere near as much.
2.) My old Windows notebook (A Sager NP5680, if you must know), weighted a bajillion pounds. It was designed for the gamer, so I can't really fault it for not being super-portable, but I needed one I could haul around and the Powerbook fit that perfectly.
3.) The feature set of the Powerbook - and OSX - is absolutely phenomenal. I'm thrilled with all the little extras because I actually use a lot of them. Does it make me more productive? Not really, and in fact playing with Expose probably makes me a little less so (because I'll use the hotcorner just to watch the animation), but I really feel there is a higher inherent value here.
4.) The absolute *lack* of having to futz with the machine out of the box. I didn't have to spend hours reconfiguring menus, removing the garbage that comes with a pre-built system (or the endless tweaking with a homebrew), or anything. I just entered a few bits of information and was off and running.
5.) The construction of my Powerbook feels much more solid than any other machine I've owned. The fit, finish and quality of materials and worksmanship seems simply beyond reproach. Unlike some other machines I've purchased, the Powerbook simply *feels* like it was worth the (admittedly quite high) price.
Of course, these are all highly personal reasons, and your mileage may vary. Unlike many "switchers," I feel no particular animosity towards the Windows side of things - I kept my Windows install up and it never, ever annoyed me. The hard crashes I had I can count on the fingers of one hand over the past two years. I only formatted it once, and that wasn't out of necessity, it was to create an OS and data partition for easier backups. I feel that OSX and Windows are equally good means to an end, but that you will have to do more work with Windows, but the payoff is that compatibility is easier. OSX is catching up fast, but let's face it, there are some things you just can't do (easily) on a Mac, which is why I still *have* my old Windows notebook.
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