Re:But how stable is it? (Score 3)

Think of it this way: forget MacOS. OS X is NeXTStep using a BSD kernel instead of a Mach kernel.

Actually, Mac OS X uses a Mach kernel with a BSD layer, just like NeXTStep.

Ingredients for OS X:

- Darwin core (Mach + BSD, in an open source package)

- Classic, Carbon, Cocoa APIs (Classic: for MacOS 8/9 compatibility ; Carbon: updated OS 8/9 apps that take advantage of memory protection, preemptive multitasking and Aqua interface; Cocoa: cool object-oriented API)

- Quartz display system (for 2D)

- OpenGL (for 3D)

- Aqua (the GUI)

Hope that clears things up for those less familiar with OS X.