It's mostly Christmas music this week, except for the Washington Opera's bone-chilling "The Medium," rib-tickling "The Telephone" and ear-pleasing "La Sonnambula" in the Terrace Theater.

The National Symphony is doing Handel's "Messiah" this week, with the Oratorio Society singing and baroque specialist Vittorio Negri conducting.

Other Christmas programs -- all being given today -- include the Paul Hill Chorale in the Kennedy Center Concert Hall; the Maryland Boy Choir in Tawes Recital Hall at the University of Maryland; the Navy Band at Constitution Hall; the Madrigal Singers of Washington Cathedral and St. Albans School at the Cathedral; and the Circle Singers at Westmoreland United Church of Christ in Bethesda. The Choral Arts Society will give three performances of its Christmas program at the Kennedy Center beginning on Tuesday evening. The Baltimore Consort will perform Renaissance Christmas music in its original forms Friday night at the Bradley Hills Presbyterian Church. In the same place on Saturday night, the Washington Camerata will give a program of old carols in the old style.

A Hanukah program will be given Saturday night in the Kennedy Center Concert Hall.

Also seasonal (today being Beethoven's birthday) is a program of Beethoven sonatas by violinist William Steck and pianist Andrew Litton today at the Wolf Trap Barns. Beethoven will also be on the program of the Euterpe Chamber Players tonight at the Reston Community Center.

Another birthday, that of Antonio Stradivari, will be observed by the Juilliard String Quartet Wednesday night at the Library of Congress. No seasonal implications can be found in the all-Brahms program by the Smithsonian Chamber Players scheduled for Thursday night in the Hall of Musical Instruments. DANCE

Today is last chance to catch the Joffrey Ballet -- which has been performing superbly -- in its final two repertory programs at the Kennedy Center Opera House.

The Washington Ballet's "Nutcracker," dressed this year in designer Carl Michel's new costumes, resumes today at Lisner Auditorium and continues through the end of the month (Dec. 29).

Tuesday night marks the opening of American Ballet Theatre's three-week engagement at the Kennedy Center Opera House. Highlights of the first week's repertory include the premiere of the company's new production of Balanchine's "Donizetti Variations" on opening night, and the world premiere of David Gordon's "Field, Chair and Mountain" Thursday evening. FILM

Pick of the week is "Pinocchio," the Walt Disney masterpiece, being rereleased Friday at area theaters.

Tuesday through Thursday, the Biograph will show the classic comedy collaborations of Howard Hawks and Cary Grant, "His Girl Friday" and "Bringing Up Baby," two of the most pleasurable movies on anyone's Christmas list.

Wednesday at noon in the Carmichael Auditorium of the National Museum of American History (and for free) the original 1932 "Frankenstein" will be shown. Horror movies never got any better.

Tuesday and Wednesday, the Circle Theatre is reviving "Chinatown," Roman Polanski's riveting film noir nouveau, starring Jack Nicholson in one of his most magnetic performances; Thursday through Saturday, "Tootsie," the best comedy of the '80s.

Among current releases, "Beverly Hills Cop," starring Eddie Murphy and riddled with bullets and laughs; Francis Ford Coppola's "The Cotton Club," the most entertaining art-house movie of the year; and David Lynch's "Dune" which, for all its many faults, still dwarfs the other sci-fi movies glutting neighborhood screens. POP MUSIC

Somewhere inside Soft White Underbelly lurks the better part of Blue Oyster Cult. Mystery compounded at the Bayou tomorrow.

Pianist Cedar Walton, one of the finest accompanists in jazz, is also one of the most assured and melodically inventive. At the One Step Down Friday and Saturday. THEATER

Neil Simon's most endearing comedy yet, "Brighton Beach Memoirs" (at the National) is the playwright's account of growing up, poor and Jewish, in the Brighton Beach section of Brooklyn just before World War II. Simon has always been a funny man, but here he shows he has a big heart, too. "Gospel at Colonus" (at Arena) is the season's most distinctive musical -- an improbable but uplifting marriage of Greek tragedy and American gospel songs.