I don't have access to a N2, but thats a good idea.
To Upload a jpeg to the N2 you have to do the following:
1.Burn a CD-R (-RW) with the JPEG image(s) you desire to upload
2.Insert the CD-R (-RW) to the disc-loading slot.
3.Touch “Settings” in the Main menu, and then touch “Background Picture Setting”.The picture selected for each screen is indicated on the right side of “AV Background” and “Navigation Background” items.
4.Touch “Navigation Background” or “AV Background”.
5.Touch “Import from Disc”.The list of the pictures stored on the CD-R (-RW) is displayed.
6.Touch a picture you want for the background.
7.Select how to display the picture. "Center”: Selected picture is displayed at the center of the screen. “Repeat”: Selected picture is patterned, and displayed as covering the whole screen.
8.Touch “Done”
I have heard that the DVD's have no copy protection and can be backed up. I will try it when I get a chance though.
When you load a jpeg onto the N2, it loads it into the onboard memory, not the DVD. There is no way of getting a jpeg image from the N2 onto the D1.