Any Links to PC Based CNC Retrofits or Tutorials?

I was referred to this group from the newsgroup alt.machines.cnc
hopefully I'm in the right place for advice! :-)

I'd like to know more of what's involved in doing a Home brew PC
based CNC retrofit. I'm going to look at a CNC Bridgeport Mill
tonight. Control is gone but I'm told the rest of the mill is
complete. At this point I don't know which mill it is other than its
not a fixed ram machine and "looks" like a regular manual Bridgeport
other than its strictly CNC controlled. Has a 2hp Variable Speed
head. I'm on a super restricted budget so it I'm looking at PC based
EMC software etc. using the drives that are on the machine.

Anyone ever document such a retrofit or conversion and put it up on
a website? I'd like to "learn" a little more as to what might be
involved...

Thanks in advance.
Marty