This cannot be done within Limewire. If you use iTunes you can create separate playlists for each of you and can also have the same songs on different playlists if you have a mind to
The play lists can be sorted by artist, album or almost anything else. Also it plays your tunes infinitely better than the Limewire player.
Perhaps other applications can do this as well, but iTunes does it well for me. It is a free download from Apple
http://www.apple.com/itunes/
Let us know if you need any more help