Future CNC man

I plan in th near future to setup a CNC for a 3-n-1 system. I have
not worked all the details out on the hardware side, but I was
wanting to know what is needed from the software side to get the end
results on the CNC machine. I'm a user of Autocad and wish to stay
with it. What is involved in taking a Autocad file and turning it
into a working part. I see lots of refrences to EMC for linux. Would
files move from the NT Autocad enviroment to the Linux and is there
some sort of file conversion? Anyway I'm trying to visualize what's
involved on the software side of things. LIke I said though I would
like to use my Autocad files.

Thanks for answering my newbie questions. I hope to be in the CNC
world soon. Looks to cool not to do.

Shawn