Some 31 million viewers tuned in to President Obama's speech on Afghanistan on the broadcast networks Tuesday night. CBS roped in 10.16 million of them, according to preliminary figures released early today (Wednesday) by Nielsen Research. Another 8.65 million watched the president on NBC; 7.46 million on ABC; and 4.57 million on Fox. Cable ratings for the speech were not immediately available. Later in the evening, a repeat of CBS's NCIS was able to prevail over mostly all-new programming on the other networks. But NBC took over the lead at 10 00 p.m. with The Biggest Loser, which continues to be its biggest winner among entertainment programs.