GOOD MORNING: They knew he was coming, so they baked a cake. The “they” was NBC, led by Don Ohlmeyer; the “he” was Robert Halmi, whose “Merlin” conjured up magical numbers for the network. Halmi whisked in Tuesday from N.Y. for a coupla hours in Burbank, where the Peacock proudly welcomed him. “That cake meant more to me than money,” Halmi claimed. But, he added, they did start talks for more — maybe four-five epic minis to follow “Merlin,” “Noah’s Ark” and “Crime and Punishment.” Halmi says he’ll continue the relationship there because “they have vision and they let me dream. No one else gave me that ($ame) freedom as with ‘Gulliver’ and ‘The Odyssey.’ ” “Merlin” goes out internationally, sold in every country in the world, Halmi enthused. “And only to be shown on TV. It belongs on TV. The (theatrical) feature world is not for me. I like to be able to tell my story — to dream, to fantasize, to use your imagination. Reality sets in soon enough! People forgot how to dream.” Halmi said Ohlmeyer admitted he cried when viewing “Merlin” and said, “I never thought TV could be that good.” … Pre-production starts on “Noah’s Ark” in Melbourne next week, with a 14-16 week sked in the same $25-30 million budget range. John Irvin directs. Jon Voight, who will play Noah, phoned from Brussels, where he’s starring in a remake of the classic “A Dog of Flanders” for director Kevin Brodie, with Jason Robards and Cheryl Ladd. Voight (59) plays a man of 36 in the pic. “I look like a young leading man, ” he laughed. “But, I hope audiences like me for my acting.” Voight stated, “I know I’m not going to get a facelift” — so, he brought his makeup and hair experts, Kenny Diaz and Dino Ganziano, with him on this (and all films). May 6, Voight, who completed “The General” for John Boorman pre-”Flanders,” next heads to Austin, Texas, for his football coaching role in “Varsity Blues” before donning his beard as Noah.THEY SCREAMED, THEY YELLED, they laughed — it’s the sleeper of the summer.” That’s the modest report from Tom Sherak from Lake Tahoe, where 20th’s sales conventioneers, branch and division sales managers saw “Something About Mary” Monday night. The Bobby and Peter Farrelly pic, starring Cameron Diaz, Matt Dillon and Ben Stiller, originally skedded for Christmas, goes out to over 2,000 screens July 15. “Something” came in for around $16 million, making it eligible to be in the big “sleeper” category. 20th’s big budgeters (you-know-what-that-means) “X-Files” and “Dr. Dolittle” go out June 19 and June 26, respectively — leading up to “Something.” … 20th’s Bill Mechanic chairs this year’s Vision Awards June 20 at the BevHilton with Sherry Lansing as co-chair. Mike Myers m.c’s. Arnon Milchan receives the Lifetime Achievement Award. Directors to be honored for their “Vision”: Richard Donner, Arthur Hiller and Robert Wise. Producer honorees: Lawrence Bender, Jon Peters, Jerry Weintraub. Women of Vision: Suzanne de Passe, Carole Black, Dayna Flanagan and Pat Mitchell. For Television: Brad Siegel. “Artists of Vision”: Helen Hunt, Edward James Olmos, Marlee Matlin, Matt Damon, John Cusack. Yours Truly hosts. … The 10th World Music Awards tapes May 6 in Monaco, with Gloria Estefan and Jason Priestley hosting. Co-hosting are Daisy Fuentes, Keenen Ivory Wayans and Damon Wayans, with performances by Mariah Carey, Sean “Puffy” Combs, Hanson, Gloria Estefan, Back Street Boys, Savage Garden, All Saints, Luis Miguel and Andrea Bocelli. Prince Albert presents Carey with the World’s Best Selling Artist of the ’90s Award. Gary Pudney, Melissa Corkin and John Martinoff exec produce Lyricist Ray Evans (“Mona Lisa,” “Silver Bells,” etc., written with composer Jay Livingston) receives the St. Bonaventure U. Arts Award Saturday. It honors a person from the region. Evans is from nearby Salamanca (N.Y.), where a theater’s also named for him. MAUREEN REAGAN RECEIVES the Gold Triangle award from the American Academy of Dermatology, Thursday at the Waldorf. She went public on her malignant melanoma on “20/20.” The award is for her heroism in raising the American public’s awareness of melanoma and promoting annual skin examinations. “Seinfeld” is also awarded for a seg noting skin care awareness, as are reps from b’cast and print journalism. … Looking ahead to global showbiz in the millennium and after, and coming to L.A. from N.Y. next week to help raise $40 million: Bill Rollnick and wife Nancy Ellison R. They’re appointed by President Clinton as U.S. Commissioner General and Deputy Commissioner, respectively, to the World’s Fair in Hanover in the year 2000. The funds will build and operate the U.S. Pavilion in Hanover, to be used for future cultural and entertainment phenomena — like preems of major studio movies to be released globally post-fair dates. Rollnick, on the board of the Metropolitan Opera, is the largest stockholder of the Mattel Corp. Wife Nancy is on the board of the American Ballet Theater. … Israeli rock star Danny Sanderson headlines the Israel Independence Day Community Festival at the Pan Pacific Park in L.A. Sunday.