Jeff:
First of all do not use Timer 0. Find a derivative with a PCA. Then read the Intel PCA Cookbook.....see it here. This will tell you everything you need to know about easily measuring pulse width, period and even duty cycle.

Michael Karas

BTW the above link is also in the 8052.com Links page. (See the Interesting Sites section of the Links Page by pressing the Links button to the left).
MJK