This song is called Rose Moon, and it's by Ali Project. Ali Project does a few themes for Rozen Maiden and Code Geass if anyone's ever heard of those anime, and this song is one of their older works. Their newer stuff is much darker and more mysterious.
http://www.youtube.com/watch?v=Tt1yrA-T6zY&playnext=16&playnext_from=QL
The Sailor Moon Guild
A guild for those who love Sailor Moon. (Big Fourum RP needs more players).