3 hard drives in Me, 2 in XP

 I recently upgraded from Windows ME to XP home edition.  after the upgrade, one of the drives ( the one with all of my music on it) does not show up.  It is no where to be found in XP however, when I turn on the computer, the option to start ME is there.  If I go to ME, the third drive shows up though none of the music is on it.  any ideas about what happened and what can i do about it?  I fairly new to this computer stuff so talk slowly.  
thanks,
karl