Fox injected a little life into its dismal summer season last week thanks to a reality series about wife-swapping.

Last Tuesday's debut of "Trading Spouses: Meet Your New Mommy" (concept: mothers from very different families switch places and drive their new broods crazy) drew the biggest audience from the coveted 18-to-49-year-old demographic for any of this summer's new crop of unscripted shows. And there have been more than a few.

"Spouses," which attracted a modest 7.5 million viewers, also managed to topple a new episode of "Extreme Makeover," which ABC aired opposite the Fox show in an attempt to draw away viewers.

Despite the success of "Spouses," Fox finished fourth for the week in the Nielsen ratings race with an average of just over 5 million viewers.

Led by its "CSI" franchise, CBS won, as it has almost every week this summer, averaging nearly 8 million viewers. The network also got a boost from "Amazing Race 5"; its audience of 11.1 million last Tuesday was its largest of the season.

NBC, which saw its puniest Thursday night audience in history with four "Scrubs" repeats and an "ER" rerun, managed a second-place finish with a 6.5 million viewer average. ABC finished third for the week with 5.7 million.

While broadcast ratings continue to sag this summer, some cable offerings are drawing significant audiences and, at times, beating out their broadcast brethren.

The debut of FX's firefighter drama "Rescue Me" garnered 4.1 million viewers Wednesday, making it the seventh-highest-rated cable series debut in history and the third highest among 18-to-49-year-olds. The "Rescue Me" audience also outdrew ABC's season finale of "The Ultimate Love Test" by about 700,000 viewers.

USA Network's short-run sci-fi drama "The 4400" continues to soar. Sunday's third installment averaged 5.5 million viewers, basic cable's top-ranked prime-time show of the week.

The Red Sox-Yankees rivalry lives on and ESPN is thrilled. Sunday night's game, in which the Bosox spanked the Yanks, was watched by 5.3 million people, the biggest audience ever in the 15-year history of the sports network's Sunday night game of the week.

The week's top 10 programs, in order, were: CBS's "CSI," "Without a Trace," "CSI: Miami," "Amazing Race 5," "Two and a Half Men" and "Everybody Loves Raymond"; NBC's "Law & Order" and "Law & Order: SVU"; and CBS's "Cold Case" and "60 Minutes."