I see that there is an option to sync ringtones on the new iTunes. But, how do you get the ringtones? I'm sure this is already posted on here, I just don't feel like searching right now...
If you have legally purchased music through the iTunes store, a bell will be next to the song title. Only those songs can be used to sync as ringtones.
If you haven't purchased the music, then do the search on custom ringtones for iTunes 7.4 or 7.4.1. There is a easy 'work-a-round to use any song.