thanks to all for this board - been learning a lot by lurking...
I have taken the plunge and just bought a generic jamma cabinet, and plan on using for a MAME conversion. The monitor is faulty, so I intend to go the PC Monitor route (I have a 19" one spare), and strip out all the Jamma stuff. It is a standard 2 joys/4 buttons per player/ 1/2 p start button.
The decision I have is between the I-PAC and the minipac....
The wiring is already in place for the controls, so I guess I could just cut&strip the wires at the loom and wire directly into the I-PAC. Or I could rip everything out and use the minipac & wiring harness to connect to the control panel with fresh cable.
I have no immediate plans for a spinner or trackball, but you know how these things go, I may well do in the future.

Any recommendations for me to choose between the I-Pac or Minipac? There doesn