I don't know anyone who replaced their Mac OS with Windows. However, there are a few programs that you can buy that enable you to keep your Mac OS, and also run Windows as if it were an application and not its own operating system. So "installing windows" in this context is about as extensive as you "installing middleware software" on your windows computer.

I used to hate the Mac until I bought one. It's 99% compatible with everything that I do, and this 1% of the time that I need help on something like the DoD CAC readers isn't really that much of a hassle.

I've had XP and Vista... and I was always fighting to reinstall drivers, download updates, slow down my system with add on virus protection that didn't do anything against spyware, etc.

I can honestly say that the Mac is superior.