UNVEILED: Singer Marc Anthony, 32, appeared at a Manhattan press conference with Gov. George Pataki on Thursday to debut a TV commercial for the popular "I Love New York" ad campaign, reports the Associated Press. There are actually two versions of Anthony's commercial (in which someone confuses him for Ricky Martin): one in English, the other in Spanish . . . HIRED: Former "Happy Days" actor Henry Winkler, 56, also known as "The Fonz," is joining the syndicated game show "Hollywood Squares" behind the scenes, as an executive producer, reports Variety. The show has been slipping in popularity, and center square Whoopi Goldberg will not be returning next season, reputedly over a salary dispute, news reports said earlier this month . . . CLARIFIED: Dr. Robert Atkins, 71, whose best-selling "Dr. Atkins' New Diet Revolution" promotes a controversial high-fat, low-carbohydrate diet, said in a statement that he is recovering from cardiac arrest caused by a heart infection. "This was not a heart attack but a cardiac arrest related to an infection of the heart he has been suffering from for a few years," Atkins said in his statement, as was reported by the AP. His recent trouble, the statement said, "is in no way related to diet" . . . NOTED: Veteran Variety columnist Army Archerd, 80, celebrates the 50th anniversary of his show-business column on Friday, which for the past half-century he has opened with an unfailingly chipper "GOOD MORNING." Army, good morning to you.