Dudley Moore may have Progressive Supranuclear Palsy, a relative of Parkinson's disease, but he also still has a sense of humor. In an open letter about April 16's "An All-Star Tribute to Dudley Moore," the "Arthur" and "10" star writes that he is inviting everyone "to help me in celebrating my 66th birthday this coming Monday. It's a very low-key affair at a little place . . . Carnegie Hall." He goes on to say, "You can only imagine how my supposed friends are going to try to embarrass me with clips from the many movies I've made -- fortunately there are a couple of duds by ol' Dud that they won't be able to find, even at a discount video store." Robin Williams and John Cleese, who cannot attend in person, will be seen in newly filmed messages to be screened at the event, which is being chaired by Michael Caine and Julie Andrews. Those due to pay tribute on stage Monday include Mary Tyler Moore, Chevy Chase, Jimmy Fallon, Bo Derek, Eric Idle and Barbara Walters. Proceeds from the event will benefit two of Moore's charities. "P.S.," adds Moore. "Please learn all the words to 'Happy Birthday.' It's so embarrassing when you see people trying to fake it."