Remote patrol

Tonight marks the end of the all-important November ratings "sweep. " So the networks are pulling out the stops to keep their dropping audience levels (and thus ad rates) from falling through the floor. CBS has a Celine Dion special at 8 p.m. on Channel 5 and Fox is re-airing "The Lost World" at 7 on Channel 4 (blowing out WDAF's 9 p.m. news in the process). A second "Dharma & Greg" airs at 8:30 p.m. on Channel 9 because "The Secret Lives of Men," which used to air at that time, was apparently a secret to most of the viewing public. PBS, which doesn't even sell advertising time, is putting on its own blockbuster, the three-hour "Nerds 2.0.1: A Brief History of the Internet" featuring compuscribe Robert X. Cringely at 7 p.m. on Channel 19. As if that weren't enough, the final "Babylon 5" airs at 9 tonight on TNT.