WORTH NOTING ON TV

* SATURDAY

Star Trek: The Next Generation (ABC, 8-10 p.m.): Trekkies may cry. This two-hour episode marks the end of seven seasons, 16 Emmies, and 178 episodes of the science-fiction adventure show. The finale, titled ``All Good Things...,'' finds Capt. Jean-Luc Picard traveling through time uncontrollably and meeting an old foe. * SUNDAY

Indianapolis 500 (NBC, 11 a.m. to conclusion): This will be the 78th running of the most famous automobile race in the world. Speedway flags will wave for 33 drivers this year, among them defending champ Emerson Fittipaldi; Al Unser, Jr.; Scott Brayton; Bobby Rahal; Michael Andretti, and Mario Andretti. This is Mario Andretti's 29th and final Indy, as he plans to retire after the season. Race fans will be watching to see how the Penske team's new Mercedes-Benz engine performs.

National Memorial Day Concert (PBS, 7:30-9 p.m. EDT): The National Symphony Orchestra's musical salute honoring veterans of World War II and American nurses of the Vietnam War, broadcast live from the west lawn of the United States Capitol.

The Elephants of Timbuktu (A&E, 8-9 p.m.): Part of the Smithsonian Expedition Specials, this documentary profiles a herd of elephants that lives close to the Kel-Tamashek people and in harmony with them. Now, ecological imbalance threatens the elephants' well-being. * MONDAY

NBA playoffs (NBC, 3:30 p.m. EDT to conclusion): Game 4 of the Eastern Conference finals between the New York Knicks and the Indiana Pacers.

Normandy: The Great Crusade (Discovery, 9-11 p.m.): Commemorating the 50th anniversary of D-Day, this documentary deftly uses letters and diaries of ``ordinary'' people to give viewers insight into the historic invasion and World War II. The diary of Marie-Louise Osmont, for example, provides the perspective of a French woman whose chateau was occupied by the Nazis. Actor Charles Durning narrates. (The show repeats late Monday night, and again Wednesday, Saturday, and Sunday.)

Please check local listings for these programs.