timming a event by arduino

hai friends ..for my project i want to calculate the time taken by a task and store it ..again when i signals the microcontroller it should able to do the same takes for the same time....i planned to give a square wave input to the controller as soon as the task starts to calculate time using raising or falling edge of the wave and it is stopped when the task ends. so now i have the time of the task in some register now i have to save it and retrieve it whe i need for this waht i have to use ?? timer1?
if so how to copy the content of the input capture register and save it some place???
is this idea is right or there is any other way????give some codes

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http://arduino.cc/forum/index.php/topic,123006.0.html