OK - I have a similar problem. I have 13 days of music (all loaded from CD) on my Ipod and my old desktop with Itunes is dead. Very dead.
I have set up Itunes on another computer now but am scared to connect my Ipod to it as if it syncs, it will wipe my Ipod. I do not want to load 13 days of music from CD again.
I have a ton of new music that I want to put on my Ipod but don't want to lose whats already on it. I know it can be done, but I can't start playing around without risking losing it all - trial and error isn't an option !