Saturday, October 17, 6 p.m.  X-Men (our 65-voice ensemble of student performers) and Ensemble X (the school's audition 27-voice choral group) will perform works by Billy Joel and Earth, Wind & Fire, songs from Germany and Estonia and solos and small group performances by singers from both groups.  Location:  Walter C. Deye, SJ Performance Center; St. Xavier High School; 600 W North Bend Road; Cincinnati.  Tickets are $8 for adults/$6 for students.  Call 761-7600 for more information.