This article was updated at 7:09 p.m.

Fox is heading into tonight’s “American Idol” finale on a wave of momentum after winning the season’s final full week in key demos.

While CBS drew the largest audience overall for the May 17-23 frame (12.1 million), according to Nielsen, Fox easily prevailed in adults 18-49 (4.4/13) while also winning in adults 25-54 (4.5/12) and adults 18-34 (4.1/14).

Net rode two hours of the music talent skein and also got a slight boost from additional “Idol” programming: two repeat hours of auditions from January on Thursday and a Sunday spec on the “Phenomenon” the show has caused.

“Idol” topped the week’s rankings in 18-49, with Tuesday’s performance episode grabbing a 10.0/28 and Wednesday’s results show a 9.8/23.

Fox also scored big with Wednesday’s season finale of “That ’70s Show” (6.7/19, 13.47 million viewers overall), which delivered some of the laffer’s best scores to date. Web also received solid perfs from Tuesday drama “24” (5.1/13 in 18-49, 10.97m) and Monday reality skein “The Swan” (4.4/11 in 18-49, 9.71m).

Big Apple bounce

CBS, second for the week in 18-49 (tied with NBC at 3.4/10), received record numbers from Monday’s “CSI: Miami” (9.0/22, 23.08m), which introduced characters from the fall’s Gotham-based spinoff. Thursday dramas “CSI” (8.8/24 in 18-49, 25.40m) and “Without a Trace” (6.3/18 in 18-49, 19.62m) both ended their seasons with winning results.

NBC similarly was led by top dramas “Law & Order: SVU” (a series-record 7.4/19 in 18-49, 18.36m), “Law & Order” (6.5/16 in 18-49, 19.46m) and “Crossing Jordan” (4.8/12 in 18-49, 12.94m).

Net aired an unusually high number of repeats for a sweep week, and didn’t generate much Thursday for a repeat of the “Friends” series finale (3.3/9 in 18-49, 7.15m) or its umpteenth airing of “Jurassic Park” on Saturday (fourth-place 1.6/5 in 18-49, 4.32m).

ABC remained fourth but put up its best weekly numbers in three months, boosted by the two-hour season finale of “The Bachelor” on Wednesday (6.0/15 in 18-49, 13.07m) and another standout perf by “Extreme Makeover: Home Edition” (5.3/14 in 18-49, 13.20m), which was Sunday’s No. 1 show in 18-49 for a second straight week.

The WB moved up to fourth for the week in persons 12-34 (2.1/7) and more than doubled UPN in adults 18-34 (2.1/7 vs. 1.0/3). Frog was led by the series finale of “Angel” (Daily Variety, May 21) and also received strong season-ending perfs from “7th Heaven,” “Gilmore Girls” and “Smallville.”

Three big pro basketball playoff games, including Sunday’s Los Angeles Lakers-Minnesota Timberwolves battle that averaged 8.16 million viewers, helped TNT to an easy primetime victory over its basic-cable rivals. Among entertainment series, MTV’s “The Real World” rated No. 1 in adults 18-49 (2.4/6) and adults 18-34 (3.9/11).

Comedy Central enjoyed one of the best days in its history Sunday, powered by standup spec “Larry the Cable Guy: Git-R-Done” (1.5/4 in 18-49, 2.81m).

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On Monday of the current week, CBS rolled behind its dominant 9-11 p.m. block, taking the night easily in 18-49, 25-54 and total viewers.

“CSI: Miami” (8.1/20 in 18-49, 21.30m) closed its second season as Monday’s top show, but the Eye also saw strong showings by laffers “Everybody Loves Raymond” (6.4/16 in 18-49, 18.33m) and “Two and a Half Men” (6.6/16 in 18-49, 18.16m), the latter of which hit a new high in 18-49.

Fox’s “The Swan” ended with a pair of episodes, including the 9 o’clock pageant finale that produced the show’s best Monday scores of the season (4.9/12 in 18-49, 10.75m). It led its hour in persons 12-34 (4.6/13).

NBC had a soft night with all repeats, led by “Fear Factor” at 8 (3.7/11 in adults 18-49, 9.5 million viewers overall), while ABC struggled with the premiere of theatrical “A Beautiful Mind” (2.0/5 in 18-49, 6.12m).

UPN was solid with one-hour season finales of laffers “Eve” (1.5/5 in 18-49, 3.53m) and “Girlfriends” (1.8/5, 3.78m).