If this was going in something that never saw the dirt and was used for long drives then maybe it'd be nice to have the dvd stuff. but I'm with Est. throw in a thomas guide or get a little handheld gps unit...they've gotten pretty reasonably priced. and I already made the mistake of putting a nice face unit in my truck. It lasted maybe a year before it was full of dust,dirt,sand. If she's set on being able to watch movies why not look into a portable dvd player.
If you went all handheld stuff you could probably get the same type of stuff she wants(maybe just not as nice) for half the price. and you'd have the conviniece of being able to use it in any vehicle.