AVR-Chat

Hello All!
I am just getting started into AVR's.  I am seeking help on a 
circuit.  I need to build a tachometer with opitcal pick up.  The max 
RPM to be counted will be around 200,000 RPM.  I was told that pretty 
much all of the tasks could be handled in code with a 
microcontroller.  My pickup is a Phototransistor/LED its set up to 
give one pulse per revolution.  So basically all I need is a 
frequency counter with a 1 sec gate time, and then multiply the value 
by 60,(my guess)Then to display the data on a 6 digit LED display.  
I don't know really anything about M.C's but bought a few 28 pin 
Mega8 chips to experiment with.  What should the circuit look like?
I am thinking the only thing I need on the board would be the display 
+ multiplexing components and the Mega8 with a connector runing from 
a input pin(interupt pin?)Let me know if I am on the right track.  Or 
if someone else has built one of these.  Any help would be greatly 
appreciated!

Thanks
Happy Holidays
William Nachefski