It's because of VMware Fusion and Parallels. Simple.

My next system will probably be a Mac primarily running Windows 7 or 8 where I'm currently the most invested. The ability to have both in the same box justifies the extra cost of a Mac to me. My older XP music production system is actually a VMware Fusion virtual machine running on an older MacBook and used mostly for the XP apps.

Both integrate flawlessly on my home network where I use TeamViewer to access them from what is currently my main Windows machine.