If you feel a disturbance in the Force, there's good reason: After years of anticipation, the classic ''Star Wars Trilogy'' will be released on DVD Sept. 21 -- quite a shift from the original plan to hit stores after ''Star Wars: Episode III'''s arrival in theaters next year. This comes in the wake of other news from the Empire:
-- Recently leaked behind-the-scenes footage from ''Episode III'' gave a glimpse of Darth Vader in his ''Luke, I am your father'' getup. Back in black? All right!
-- The Cartoon Network's George Lucas-sanctioned ''Clone Wars'' shorts will introduce a villain who'll also appear in ''Episode III.'' Look for it in ''Clone Wars''' Episode 20, coming up.
The four-disc Star Wars DVD set will comprise the 1997 special-edition versions (now on VHS), and will rename the original 1977 film ''Star Wars: Episode IV -- A New Hope.'' (After all, the latest films are prequels.) And if the $50 million-earning DVD release of another retro set, ''The Adventures of Indiana Jones,'' is any indication, the ''Trilogy'' will be an earnings force to be reckoned with.