I've started to build my ROV and have decided I could use an I/O Board and Sonar if I ever want to get this thing autonomus or even semi autonomus. I want to make sure I'm getting everythign I need for this and that they will be compatible...

I'm looking at:

Arduino Duemilanove and Parallax's PING Sonar mounted on a pan and tilt kit

besides those 2 components would there be any other hardware needed? I'm also thinking I can replace my phidgets adv servo controller when this is installed (its only controlling a pan and tilt setup).