3 axis 9x49 retrofit recomendations.

Sorry to ask such a general question, but there is SO much
information, I'm having trouble processing it all.

I have a plain old 9x49 enco mill. I'd like to retrofit it to 3 axis
cnc. (maybe 4 w/rotary table)
I'm perfectly capable of fabricating all the brackets and hardware
but I'm over my head on the controll system. I believe I'd like to
have linear positioning feedback from some dro, not rely just on my
crappy leadscrews. also would need to be able to use the mill
manually most of the time, and have a dro function.

I'm a solid modeler by trade and fairly handy with computers, I have
a few pc's and a hpux workstation, or could set up linux.

what would you recomend for a somewhat economical approach?

thank you very much,
Dan