I switched from Windows to the Mac in 1993, but have kept limited Windows capability around since then.
While Apple was getting OS X ready, I was trying various brands of Linux, settling on Mandrake.
I like the ideals of free software and open source, but there are still too many little things in Linux that don't work right. Mac OS X gives me fewer headaches.
So I still have Windows and Linux available, but I find myself using the Mac 99% of the time. It just works better for most of the stuff I do.