It's me with the GPS-wanting techno-ignorant dad, back again.

After looking at Garmin's lineup a bit more, I think Dad would appreciate a GPS that spoke street names, so the c530 is out.

I'm trying to decide between the c550 and the nuvi 350. As far as I can tell, the main differences are that the c550 is bigger, has a built-in traffic receiver (which he'll never use) and has bluetooth (which I doubt he'll use).

Are there other differences? Are they equally sensitive and quick at locking in a signal? Are the screens the same size (I know they're the same resolution)?