Bill Murray, the very first guest on NBC's Late Night with David Letterman, will help Dave celebrate 25 years in late-night TV this Thursday on CBS' Late Show.... Following the Feb. 3 combo of Drew Barrymore/Lily Allen, Saturday Night Live will feature Oscar front-runner Forest Whitaker as host, and Keith Urban as musical guest.... Fox has announced a Feb. 27-28, after- Idol premiere for Are You Smarter than a 5th Grader?, its new, self-explanatory quiz show.