Even a 'primitive' computer (128MB ram, 200MB hd, and an old cpu > 500Mhz) can be still usefully used in a cnc environment. Emc2 even works in a linux live Puppy Linux version (Rtai ofcourse). Everything is inside an image of only 50MB (downloadable here). It is a livelinux version but can be installed on an USB device or on a normal hard disk.
The setup is similar to any other linux distribution. Download the iso, masterize it, and start the pc.
Unfortunately, as far as we know, the project has not been updated any more but it works quite well.
