I suggest using LinxCNC as it's free and can be run directly from Boot CD ( I think.? I'm not into linx others will correct me if wrong).
I don 't think you can run a machine directly off the live linuxcnc disk. But you can use it to look at the interface and get the feel for it.
http://www.linuxcnc.org/linuxcnc-2.7-wheezy.iso Mach3 might be better to play with and the demo version will let you use it for a max of 500 lines of code.