AVR-Chat

I just posted under files a prototype schematic for my tachometer 
circuit.  Take a look and tell me what you think.  I am new to AVRs 
so let me know if I made any mistakes, or if there are changes that 
will work better.  My needs for this circuit are as follows:
Using a laser or led (optical pickup) to measure pulses from the 
rotar of a turbine engine.  I have it set up to give two pulses per 
revolution.  Send pulses to the AVR where all the math is done and 
then display the calculated RPM (200,000 rpm max) on a multiplexed 
LED display.