NEW YORK -- "Big Brother" and always-popular repeats of "CSI" and "Without a Trace" lifted CBS to an overpowering win in primetime Thursday. "CSI" averaged 12.2 million viewers and a 3.9 rating/11 share in the adults 18-49 demographic, according to preliminary ratings estimates from Nielsen Media Research. It was the top show in both key measures, total viewers and the demo. Even CBS's only original show, "Big Brother" (9.6 million, 3.4/11) couldn't keep up although it was able to win its time period against weak competition. So too did "Without a Trace" (11.9 million, 3.6/10) at 10 p.m. The only other original scripted program of the night was NBC's "Windfall" (4.8 million, 1.8/5), which wrapped up its run at 10 p.m. and came in a weak third place after ABC's "Primetime" (6.9 million, 2.3/7). Nightly averages: ABC (7.5 million, 2.4/7); CBS (11.2 million, 3.6/10); NBC (5.6 million, 2.0/6); Fox (5.3 million, 1.8/5); The WB (2.2 million, 0.8/2); and UPN (2.1 million, 0.8/2).