> Would you use a thermoresistor hooked to a PIC that had an on-board A/D or
> would you use a Dallas (or equivalent) digital sensor?
> I only need approx (2 degrees or so) and it is to put on top of a roof.

I have used the SmartTemp sensor. It's really easy to work with.
Takes only one pin of the PIC.

The SMARTEC SMT160-30 is a three terminal intergrated temp sensor,
with a modulated duty-cycle output.
The output is interpetable by the PIC without A/D.

Cable length: upp to 20 meters (approx. 65 feet)

The SMT160-30 (TO18)has an overall accuracy of 0.7 C (Range: -30..100 C)
The SMT160-30 (TO18)has an overall accuracy of 1.2 C (Range: -45..130 C)


Price: (In Sweden)
 SMT160-30 TO18  48,50SEK ~ US$6,00 (For one)
 SMT160-30 TO92  35,00SEK ~ US$4,40 (For one)
 SMT160-30 TO220 35,00SEK ~ US$4,40 (For one)