Doesn't really matter I don't think. Install iTunes as per normal and add music to the library how you please and when you want to add music to your iPod, just select the necessary music you want to put on by dragging and dropping. OK, you'll have both your lots of music on the one library, but that's no big deal, just creat some playlists to avoid playing each other's on the PC. Whosever of my mates' iPods get plugged into my PC, iTunes recognises it as a separate player. Easy life.