No you didn't post it in the right spot. This is Tips & Tricks section & caters for general issues not specific to any Gnutella client app. such as BS or LW, etc.

If your 2 computers are networked then it should be easy & very quick. But since you're only connected as far as a router goes, have you tried iTunes sharing of music? I'm not totally sure whether that also allows for copying or just for playing the playlists of each other's comp. Oh & whilst I think of it, you're not on a lan anyway so that perhaps wouldn't work.

If you have ethernet cards on both then why not network them directly. Or burn the songs to a cd-rw/dvd-rw.

Another thought is if you can see the playlists from the other computer, then why not add them via importing the playlist & then consolidating them using iTunes.