Is it possible to use the TVout library and the DS18B20 one wire digital temperature sensor, to create something that prints the temperature on one line and updates the temperature without printing another line? If so, can someone help me do this?
Yes, it's entirely possible. Just use TVout.print(x, y, data); it prints data at the coordinates (x,y). I suggest including a TVout.fill(BLACK) in there somewhere too, so any differences in line length don't result in leftover bits of text.