NOPE
you can use both...2 slots

Is there going to be an IPOD/MP3 hookup?

I am using a TomTom 700.( http://tomtom.com/ )The brand appears to be fairly new to the U.S. It is a compact portable device that can be used in Europe aswell. It's easy to use. I have my Nav mounted on the dash next to the base of the A pillar, basically on top of the sideglass defogger vent. I tried mounting it above the rearview mirror but I find that I can keep my eyes on the road better with the A pillar location. Incidentally, it can also give you traffic reports and weather via a bluetooth phone. I haven't used this feature yet - I don't have a bluetooth phone yet. My friend has a TomTom 300 and is trading up to the 700.

A portable Garmin StreetPilot (such as the 2720 or c330/340) also works great. They are small, portable, offer more features, and generally are far cheaper than an OEM Nav unit or an aftermarket in-dash unit. On top of everything else, you can use them in different cars.

The down side is that you have to deal with a top-dash mount or a window mount and a power cord. Which is not nearly as slick as an integrated in-dash unit.

I'm also shying away from an in-dash system, since I plan on keeping my H3 for many years and I'd sure hate to eventual have an in-dash system that is technologically ten years behind the times. In other words, it seems easier to keep on the leading edge with a portable set-up.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H3Lady:
wait for gm, i am sure it is touch screen and the faceplate matched the dash

Here ya go

http://www.delphi.com/pdf/d/int_nav_radio.pdf </div></BLOCKQUOTE>

Thanks for that H3Lady!
I still prefer the Pioneer system as it has both DVD and CD slots and it has nice options like the iPod connector and rear view camera. Do you know if the faceplate for the factory nav unit will be available as an accessory.
Thanks,
grimley

Here's some pics of my Tomtom 700 in my WhiteH3, Driver View...

Door View...

that is where mine is too on the left side

aggiehummer...er, where did you get the mounting kit for the Eclipse navi head unit? Or what is the part number? Did you also use an adapter to connect to the factory wires?