CBS Seeking to Sign NBC's Costas: CBS, enjoying great success with David Letterman in the late-night TV wars, is going after another NBC star, talk show host and sportscaster Bob Costas. Insiders report that CBS is negotiating with Costas to host a post-Letterman talk show that would be produced and owned by Letterman's production company. Costas, a versatile interviewer whose easygoing style has led him to host many of NBC's key sporting events, has emerged as CBS' top choice for the 12:30-1:30 a.m. slot, the sources said. One possible hitch: Costas is reportedly in contract renegotiations with NBC, and CBS executives worry that he may be leveraging his talks for a better deal at NBC. Costas, who currently hosts "Later With Bob Costas" after "Late Night With Conan O'Brien," would apparently continue with his same "straight-ahead" style at CBS. Sources also stressed that NBC will probably go to great lengths to keep Costas because of last year's fiasco over losing Letterman. CBS officials could not be reached for comment.