TONIGHT'S MUST-SEE

"Terminator: The Sarah Connor Chronicles" season finale, 7 p.m., Fox. Two episodes are welded together to wrap up the season. Cameron — the teen-looking android — faces accusations from Derek (Brian Austin Green). Also, she and John face danger on a school trip. Sarah, John's mother, comes too close to a terminator. Also, she and Derek deal with an untrustworthy sort.

OF NOTE

"The Royal Family," 7 p.m., ABC. This 20/20 documentary traces a year in the world of the British royal family.

"How I Met Your Mother," 7 p.m., CBS. Parts of this rerun are excellent, as Marshall and Lily prepare for their first Thanksgiving as a married couple. And parts — involving a bet that lets Marshall slap Barney — are merely juvenile.

"In Treatment," 7:30 p.m., HBO. Last week's episode (rerunning at 7 p.m.) found a breakthrough for Laura, who finally discussed her childhood trauma. Now she returns — not as a therapy patient, but as a friend who needs to talk. It's another key episode, beautifully acted.

"Welcome to the Captain," 7:30 p.m., CBS. Josh, the young writer, has a meeting with the Paramount president. Saul wants to advise him first.

"Jump In!" (2007, Disney Channel) and "That Thing You Do!" (1996, E); both 8 p.m. Some day, we'll campaign against the random exclamation marks in titles! The E channel even puts it in its name! Still, we have to admit that these are two zestfully entertaining films. "Jump" has Corbin Bleu as a teen reluctantly joining a jump-rope team; the competitive performances are spectacular. "Thing" has Tom Everett Scott as a teen rock musician in 1964; the title song is infectious. Tom Hanks directed, co-starred and picked a fine cast, including Liv Tyler and a then-unknown Charlize Theron as Faye and Tina.

"The Pussycat Dolls Present: Girlicious," 8 p.m., CW. Nicole Scherzinger, who found success as the lead singer for Eden's Crush and the Pussycat Dolls, performs.

"Two and a Half Men," 8 p.m., CBS. In a fairly funny episode, Charlie has a new career singing to children.

"The New Adventures of Old Christine," 8:31 p.m., CBS. Having just broken up with the near-perfect Mr. Harris, Christine seeks to find herself. The answer, she soon realizes, is not to be a rock-climber. We can't vouch for this episode, but we mention it for a reason: It leads into one (8:30 p.m. March 10) that has some hilarious moments.

"Medium," 9 p.m., NBC. Allison wants to help Devalos (played by Miguel Sandoval, who directed the episode), but there's a problem: She's had a vision that his friend Garrity is involved in a horrific conspiracy. Maybe we should have known that — Garrity is played by Gregory Itzen, the unscrupulous President Logan on "24."