Homebrew PCBs

Hi all,

Firstly, thanks to those who have helpfully responded to my earlier
questions with suggestions to use CNC drills/routers.

I'm forming ideas for the mechanics of a CNC transport:
 - PIC micro controlling the thing, talking to PC via serial
 - looting the x-y rotation counter bits from an old mouse
 - implementing the x-y board transport via PWM-controlled motors,
   driving threaded rods which have the mouse rotation counters attached

I could see this achieving a resolution of 0.25mm or better.

(Shame about the chicken/egg scenario - I'd love to have the CNC
apparatus already in place to help me manufacture the PIC logic board it
depends on :P )

Software on the PC side could then have basic primitives:
 - goto (x,y) - board movement
 - goto (z) - raise/lower drill or router
 - calibrate (x,y) - allow user to check/adjust calibration relative
   to a known 'origin' on board
 - turn drill/router on/off

Where I'm stuck is with the router - what kind of bit could I use to
guarantee good results and clean polished cuts?

And, any feedback on the above?

-- 
Cheers
David