Throw the portable unit away and get a proper panel-mount kit.
The Bendix-King KLN94 is one of the best there is, full color moving map plus all the bells and whistles.
The B-King KLN89B aint bad either. Gas discharge red display is very readable in sunlight.
Have both of these units in my personal aircraft, and with over a hundred GPS approaches, no problem with RAIM...and they have been right on the mark, everytime.
For transport aircraft, the Trimble 9000 is hard to beat, superb equipment.
GPS for approaches is certainly the wave of the future...European sour grapes aside.
