encorer feedback

I'm working with one of the hobbycnc boards and was wanting to install encoders on my motors for feedback to Mach2 or some other software.
Can this be done with some type of board between the encoders and the PC?
I'm also interested in something to replace a pot to control DC motor speed via to PC.

Thanks,
Bill

If you get a "Spammers not Allowed" message, reply to wm_mcnett@...

[Non-text portions of this message have been removed]