ipac and optipac setup

[06attaker]

Have a computer with 2 usb's and a serial port in the front and 2 usb's and a serial port in the back and also of course a mouse and keyboard port.  I,m not a computer guy so the question is I was thinking of purchasing an optipac and ipac for a 2 sided cocktail with each side having a trackball, joystick and 8 buttons, so how do I know which hookup to use when ordering them because they want to know if I want usb or ps2 cable?  I want to use a trackball for a mouse with 2 mouse buttons and a player 1 and 2 button and 8 additional buttons for game play for games like asteroids, defender, etc.
Thank you!!!!

[northerngames]

ipac works like a keyboard for your buttons and joys your choice of usb or ps2 like a keyboard.

optipac works like a mouse for your trackball your choice of usb or ps2 like a mouse.

ipac makes your pc think the arcade controls are a keyboard

optipac makes your pc think the trackball is a mouse

the ipac goes in your keyboard ps2 port or any usb port

the optipac goes in your ps2 mouse port or any usb port

either works either way but if you use ps2 the opti must go in the mouse port and the ipac must go in the keyboard port