Boogie Fever

Don't expect to see the same old song and dance on the 100th episode of ''That '70s Show.'' Producers of the Fox Me-Decade comedy plan to mark the occasion this April by creating a full-on musical episode. ''It's really not too much of a departure for us because we've had a lot of musical fantasies and choreographed numbers in the past,'' says '''70s'' exec producer Jackie Filgo, who believes there's ample room for a different take on the genre beyond the recent offerings from ''Buffy the Vampire Slayer'' and ''The Drew Carey Show.'' The '70s riff will take us inside the brain of Fez (Wilmer Valderrama) just before his performance in the school's Spring Sing concert. The Who's Roger Daltrey will guest-star as an overbearing music teacher, and there'll be revamped covers of retro classics, including ''Love Hurts'' and ''Happy Together.'' Does that mean all of the actors will be showing off their vocal range? ''They're a really game cast -- they'll do anything,'' assures Jeff Filgo, Jackie's husband and fellow exec producer. ''If we have some cast members that aren't comfortable singing, we'll figure out a way to dub them.... But we'll make a joke out of it and own [up to] it, instead of trying to trick people.''