I've been faithful to Windows forever, but I've recently considered Mac...is it true that you can run Windows OS on a Mac, or did I pick that up incorrectly? Is it also true that any application for Windows can be made for Mac (I thought no before...)?
Boot Camp (dual-boot application for Macs)
VirtualBox (run pretty much any OS on any other OS)
PC versus Mac is the stupidest misnomer I've heard in a while. Macs are PCs; PC just stands for "Personal Computer." The way the commercials spin it, it's OS X versus Windows, which is equally as stupid; Boot Camp lets you run Windows on Mac hardware, and OSx86 lets you run OS X on any x86 computer.
If you're asking what hardware I use, I use non-Apple hardware. You can get something with equal or better specs to an Apple for cheaper pretty much anywhere.
If you're asking what OS I prefer, I'd answer nLited Windows XP and net-installed Fedora Linux. The nLited Windows XP is lightweight and runs my games like a charm. As for Fedora, which I use for everything else, the net install let me skip out on the bloatware that is GNOME and KDE (opted instead for openbox and pypanel, though I may switch to perlpanel instead), so I can run as many applications as I want and never get slowdowns.
I don't like OS X at all. It's pretty and has a few cool Apple applications (which cost way too much, in my opinion), but many games aren't made to run on it like they are for Windows, and Linux is just a better option for nearly anything else. I know quite a few people who use OS X, but I've just never felt the draw, myself.