Harrison Cooper wrote :
>Setpoints and storage - I need a simple RS232 type interface
>with a PC to send down the desired setpoint and to read back
>the two temperatures.

There are (many) helpful Application Notes, even with examples
at :

http://www.futureone.com/microchip/appnotes/appnotes.htm

For example :

PIC16Cxx Application Notes

- AN555 Software Implementation of Asynchronous Serial I/O

Ciao
KES