Just connect the ipod to the computer and open Gtkpod. It will ask you wether to create iTunesDB, click OK. iTunesDB is a XML file with links to every song in the ipod. Later, you can copy all the songs in the ipod to your PC music library just by dragging and dropping them in gtkpod.
My wife has an ipod MA003 that she was originally using with iTunes on a Win XP laptop. That laptop has died and she is now using a Linux Mint 7 XFCE laptop.
I've setup gtkpod_aac, but have some questions regarding the iTunesDB.
[1.] Is this a file or directory? I believe it is a file.
[2.] If I am unable to retrieve the original iTunesDB from the Win XP laptop, what is the recommended course of action for creating a new iTunesDB?