So, it's very very late right now, and I have other work I need to do before bed, so lemme keep this short.
My new programmer works, and I even got the I2C interface to work with the temperature probe!! (notice the "To Do" box on right)
The bad news is that in a fit of debugging fury, I managed to burn some bad fuses to my microcontrollers, so now I can't program them any more. I'm glad that at least managed to burn a good version of the code, so I currently have a gadget that can give me the temperature (in a round-a-bout way). I'm ordering some replacement micros.