PCs punt and leave you with all the choices to make, both hardware and software-wise. Windows doesn't come with anything for hackers out of the box. If you don't want to go through that, PCs will be very depressing. If you're willing to sit down and spend 1-8 hours tweaking and installing things the way you like it, you can have a very productive development machine on your hands, it just won't be a Unix-like one.

On the other hand, getting Xcode requires you to be involved with a stupid Apple Developer Connection program, and you don't get automatic package management like in Linux.

I just built a new PC dual booting Windows and Linux and I'm loving the hell out of it, personally; I can get performance and screen real estate that's a significant fraction of a $4500 Mac Pro system at a fraction of the price; $1500 will get you dual 22" monitors, a quad-core Intel Core 2 processor, 2 GB of fast RAM, a 320 GB SATA hard drive, and a very nice video card that's adequate for semi-serious gaming. I can be highly productive as a developer, reboot, play games for a little while to blow off steam, and then go back to my distraction-free development environment. Linux for productivity, Windows for timesinks.