R.E.M. will tape an appearance on the Fox drama "Party of Five" at a Los Angeles nightclub next Wednesday, during which they'll perform their new single, "At My Most Beautiful." At the taping, during which the band will perform as themselves in a scene set in a nightclub, 175 R.E.M. fan club members will be in the audience. The appearance will mark the Athens, Ga., band's first foray into prime-time network programming. "Who would have thought we'd ever do stuff like this?" bass player Mike Mills asked. "It's goofy stuff, but a lot of people in our office watch ['Party of Five']. It's a good show and it's a chance for us to play a whole song live on TV."