I put the AVIC-D1 into my '05 a few weeks ago. Location and angle are excellent (I don't know the '04 so can't comment). Navigation software is great in many respects - the maps and directions are amanzing - the ability to search for addresses and places of interest are not so great (for example if you want to find directions to the nearest Best Buy you can key in the name and it will pull a list of locations but the list will be in an order other than geographical distance - so you'd have try out each to see which is closet). All-in-all the nav is good but not as good as some factory navs I have used.

D1 does not play DVD movies - only DVD roms (the N2 plays movies).

D1 does not have customizable backgrounds - N2 does.

D1 has a DVD slot separate from the CD slot - N2 shares one slot (so cannot alter DVD route without putting DVD in and taking CD out).

Hmmm what else. I think the N2 has multi-source capability - nav in front while movie playing in rear.

There are a few other differences. I think feature wise the N2 beats the D1 but the D1 looks better in the '05 X (and is a few $$hundred less).

With all that said, I highly recommend you DO NOT BUY the N2 or the D1 unless you are primarily interested in the nav because the audio functionality leaves a lot to be desired.

To change bass/treble etc. you have to push a 5-way toggle in - it must be pushed in directly in the center - if it is slightly up/down or to the side it will cause the song to change - I rarely was able to do this correctly.

It is also difficult to do something simple like set play mode to random on a CD - again requires multiple button pushes beginning with the dreaded center push on the 5-way toggle.

Song titles on Mp3 discs load very slowly - makes it difficult to scroll down to say the 30th song on a disc.

iPod integration is laughable - I can't even go into how bad this is.

xM integration is cool but the logos for the station are hard coded into the operating system (and not upgradable) so if stations change (and they will) the logos become less than useful.

I could go on and on.

Yesterday I bought an Alpine CDA-9855 to replace the D1. I am planning to swap them out in the next few days. I will definitely miss the nav but am hopeful that the audio functionality will be worth it.

Good luck -