RodSTAR- I have played around some with the "guts" of a mouse! Inside, you will find something similar to this: http://cp.literature.agilent.com/lit...988-9774EN.pdf There are many different types of parts made by Agilent that can be used with a PIC. You are correct with what you say about using the sensor. You see this particular part has a serial output.

I need to get back to my own experimenting, and I am anxious to see how your project progesses. I will share any of my "revelations"!