Keeping iPod music list when reformatting

Hi
I recently moved from PC to Mac. One thing is my iPod would probably benifit for being reformatted to Mac so I can update it as needed. However is there anyway I can create a playlist of the music (in the regular iTunes folder on the mac) so I don't have to search and select to reload back to the formatted iPod? The deal is while I only have a nano I would like to have to reselect all my favorit songs again.
Thanks

 

I guess it can't be done? at least that is all I can see by searching