Eagle 642 IGPS Question?

I have the Lowrance LMS-522-IGPS and I love the unit, but I have a friend who has the eagle version listed above and it seems to be almost identical to mine with a small exception.I am not able to see the river channel darker color on his that I can on mine.Am I missing something, or does he need to buy a chip map of the local lake and install on it or what? Any help is appreciated.Would like to be able to follow the river channel by site on the gps is what I want to accomplish.I am talking about on the eagle unit now, not the Lowrance. Thanks for any help.

I am looking at the LMS-522c-IGPS. Academy has them for 399. Is it a nice upgrade from just a normal fishfinder or am I just paying to have a gps next to a normal fishfinder? I hope the question makes sense! Thanks, b49

Bump! I'm interested in an answer also since this unit interests me too.;)