There is a cheaper and easier solution than an Arduino and IC temp sensor, if you look back in the archives of the group you can find a few solution for tempo control cheap and easy to DIY.
mine is located here
http://sites.google.com/site/elettronicaarduinoesperimenti/Home/thermostat-with-ua-741You need a thermometer for the first calibration, but once you do this it will work like a charm, I'm using it for my laminator.
have fun
Sapo