Can anybody tell me if it's possible to replace the stock radio with an aftermarket when you have factory navigation? Will the stock Navigation still work?

I have a 2004 RX330 with the standard audio system, 6-CD In-Dash.

My idea is to replace the 6CD system with a 6 Disc DVD system from Pioneer. It's a double din, touch screen DVD player and I'm going to put 2 TV's in the headrests and would like to use the Pioneer In-Dash to play movies to the rear screens. I'm also planning on adding a 5 channel amp from Memphis Car Audio called the Memphis-Belle and building a custom enclosure for 1 10" subwoofer while replacing all of the speakers with Memphis Car Audio speakers.