When I was studying at university, I mostly used Unix, specifically SunOS. I became very familiar and comfortable with it (so much so that I tried running something called MiNT on my Atari ST, to simulate the environment). There were some PCs around at the time, but they were only running DOS.
Later, I started work in support, and had to learn how to use Windows 3.1. However, I stayed with Unix on my desktop. Even later, Windows 95 came out, and I started the process of moving my desktop to it.
I mention this because to Microsoft fans I am a Unix nerd. To hardcore Unix users, I am a Windows weenie. But I've never been in an uncomfortable position over my choice of operating system. I believe in using the right tool for the job, and for a long time, I never thought that there was a serious competitor to the Windows desktop in the Unix environment. For all of the hard work that has been done on systems like KDE and GNOME, they still feel like layers over X11, and that's the basic problem — X11 never evolved.
Now, the astute readers will notice that I haven't mentioned the Mac OS. I never had a chance to use it in anger until after OS X was released. And I was intrigued by it. Unix? With a decent UI? But then I never had a chance to do more than play with it. And I could never afford to throw money at Apple to buy a computer off of them, until I was really sure that I would actually use it.
So for a few years, I stuck to home-built boxes running NetBSD and Windows. And coveted the idea of having OS X. Then the Mac Mini was launched, and I immediately bought one, since it seemed churlish not to. It was cheap enough to buy without worrying about the idea of it being a useless purchase. I quickly realised I wanted to use OS X exclusively and had to invest in some more serious, and portable, hardware. That Mini went to my mother.
Now, finally, my employer is getting me a nice, shiny PowerBook. I face a fundamental change in my desktop environment, not just augmenting it with a second OS. This fills me with excitement, but also trepidation. Excitement, because I can use seriously cool software such as Quicksilver. Trepidation because I have an army of utilities and a decade of familiarity to replace.
I'm not joking, either. Probably because of my Unix background — and inveterate need to fiddle — I cannot use a stock Windows installation. I have a collection of utilities, registry changes and scripts that absolutely must be installed on the machine before I can think of doing anything. And this is not covering actual full applications that I use every day: TopStyle, Microsoft Office, Adobe Photoshop, Mozilla Firefox, et cetera. No, I'm referring to programs that allow me to right-click on a program's titlebar and have it drop to the bottom of the z-order, automatic sizing of windows, being able to press the Windows-W key combo and have the URL in my clipboard open in my browser without bringing it to the front.
Not that I mind. It gives me a proper excuse to clean out my collections of random stuff that accumulates, learn how to work more effectively by breaking bad habits, and hell, just have fun with my computer for a while. OS X? Bring it on.