Thanks Brian, I don't like taking liberties. The EMC2 Live CD at LinuxCNC is a hassle free installation and includes UBUNTU 8.04 realtime, it is best to start with this distro. It is open source, follow the links on the LinuxCNC page. It can be installed on most Debian distro's maybe with an adaption here and there. I'm not sure about Free BSD, I suppose theoretically it should be possible. But bear in mind that EMC2 runs on Realtime Kernel, so I have even installed it on the latest UBUNTU 9 release, but to run the controller, you have to reboot in the realtime kernel, so what's the point really?
Might as well stick with 8.04 if you want to use the PC as a CNC controller. I am busy with EMC2 dev for advanced processing to suite the steel cutting industry, as the current version do not support reverse running a part program and plate alignment. This is a part time project of mine.
Further to that, stability of the EMC2 system is pretty much governed by what you choose as hardware, and this is so true of Windows systems as well. Skimp on the hardware and blame yourself, not the software.
I would not compare Mach3 against EMC2, it is not comparable, they are different in many ways. I like both, and use both.
Point of interest, there is a heck of an amount of CNC controllers in the industry running with Windows, especially XP embedded. Most of them that employ realtime engines utilize propriety
software as a Windows plug in, with dire financial consequences.
No need to ask for a linux ported version of Mach3, EMC2 is similar.