Help with servo control

Hello folks, my name is James Nelson, and I own a Milltronics Centurian III
verticle knee mill. It has a proprietary computer on-board which control 3 axis of movemnt via servo motors. Of course, the machine is in fine shape, but the computer is dying. I am in the process of researching retrofit control packages for my machine. I have found many stepper conrols, but very few servo controllers. My machine uses standard servo amps with +/-10v industry standard inputs. I would prefer to use software control, in either UNIX or DOS platforms. Any help or suggestions would be greatly appreciated.

Thank you,
Jim