I am a Linux systems programmer of some experience. I recently purchased a MacBook Pro, and was impressed by the stability and reliability of the Mac OS X operating system. However, I'm a very open source person, so my attention shifted to Mac OS' open source core - Darwin. However, it seems that the effort to create a standalone Darwin OS, called the openDarwin project, was abandoned years ago. My questions are: 1) Is it possible to build a complete Darwin system from scratch i.e. from the source code of Darwin 9 provided by Apple? By complete I mean kernel, shell, all basic libraries and a GUI (I prefer GNOME). 2) From the perspective of a systems developer, what are the differences between Darwin and FreeBSD? Has anyone ever written a comparison? Will all Darwin systems programs work on FreeBSD (and vice- versa)? Sorry if these questions seem naive. I'm a newcomer to the Mac world, and couldn't find any clear answers on the internet even after hours of searching. Thanks, Atriya