Was bouncing around a few project ideas with a friend of mine, and we started talking about the possibility of making a digital walkie talkie based on Arduino/Xbee hardware. I know plenty of analog devices have been made before, but what of a digital comms system? I'm not too familiar with the hardware requirements of the MP for this - do the ATmega chips have sufficient grunt for the A/D and D/A processing? The audio stream wouldn't need to be of particularly high quality (just enough to provide decent voice comms), but implementing some digital encryption would be good. Would the Arduino be suitable for it? Any comments from those with experience in this area would be appreciated. Ta!