TONIGHT'S MUST-SEE

"Chuck," 7 p.m., NBC. Last week, the government scuttled its plan to replace Chuck with a supercomputer. That's sort of good news, because it had secret plans to kill him then. Still, he's bummed; as an ex-spy, he would finally be able to date Sarah. Now comes a dating diversion: He's supposed to attract a dangerous beauty, with advice from an "expert" (John Larroquette). There are lame subplots involving Chuck's friend and co-workers. Mostly, though, "Chuck" is again a delight.

OF NOTE

"Walk the Line" (2005), 5 p.m., FX. This Johnny Cash portrait wisely focuses on his complex romance with June Carter. There's great work from Joaquin Phoenix and an Oscar-winning Reese Witherspoon.

"I Want to Work for Diddy," 6 p.m., VH1. The winner is named.

"The Big Bang Theory," 7 p.m., CBS. Penny learns about online gambling. This is not a good thing.

"How I Met Your Mother," 7:30 p.m., CBS. Here's another way Stella doesn't fit in with Ted and his friends: They love the city; she's in the suburbs.

"Two and a Half Men," 8 p.m., CBS. It's role-reversal time: Charlie cooks; Alan dates two women.

"Heroes," 8 p.m., NBC. Peter takes dangerous steps, hoping to prevent a disaster.

"Worst Week," 8:30 p.m., CBS. The first two weeks have been terrific as a guy keeps bumbling his stay at his girlfriend's home. Tonight, he tries to repair the damage he did to her dad's portrait.

"Life," 9 p.m., NBC. A lab has been trashed and a scientist has been killed. Now there are plenty of suspects. This hour flubs one part, with a broad and cliched portrait of an animal-rights guy. The rest of the story is terrific, though, particularly the final scene between Crews and the lab's custodian.