*BSD HOWTO for Linux Users?

hideki writes "I am a long-time linux user, having used it exclusively for nearly two years now. However, I would like to expand my horizons, and FreeBSD and OpenBSD came to mind. (I like Theo de Raadt's puns, so I might try OpenBSD first. :) My question -- does anyone know of good "So, you would like to try *BSD after using Linux?" documents? What is the easiest way to learn a BSD, specifically the differences. :) "