robtillaart, thanks but the sensor is sat on my desk so I'm not that worried about integer overflow as the temperature would have to be so hot I would not be here. The LM35 outputs 10mV for 1 degree. 25 degrees is 250mv = 51 ADC units. 51 * 49 = 2891. I' need 330 odd ADC units to overflow and that would be 330 * 4.9mV = 1617 mv = 161 degrees centigrade.
Your point is taken though and I was rather blindly followed the arduino workshop book. I knew about floats but hadn't noticed the arduino supported them.
Thanks