TONIGHT'S MUST-SEE

"The Class," 7 p.m., CBS. In last week's opener, bright-eyed Ethan planned a reunion of his third-grade classmates. It was supposed to be a one-time thing. Then the suicidal Richie and the lovelorn Lina fell for each other ... and Richie inadvertently ran over her in his car. Some hilarious hospital scenes ensue tonight. They focus on three of the best young comic actors in years — Jesse Tyler Ferguson as Richie, Heather Goldenhersh as Lina and Lizzy Caplan as her acerbic twin, Kat.

"Studio 60 on the Sunset Strip," 9 p.m., NBC. Last week's show ended with the outspoken Matt and Danny (Matthew Perry and Bradley Whitford) taking over a sketch-comedy show. Now, with the world watching, they need the perfect opening for the following week's show. They come up with a dandy, so stick around to see it.

OF NOTE

"Monday Night Football," 2:30 p.m., ESPN. In the first Superdome game since Hurricane Katrina, the New Orleans Saints host the Atlanta Falcons.

"Wife Swap," 7 and 8 p.m., ABC. In a late switch, the network has dumped the two "Lost" reruns scheduled for tonight. Instead, it has these reality hours, followed at 9 p.m. by a rerun of Friday's "Men in Trees."

"How I Met Your Mother," 7:30 p.m., CBS. Last week, we saw Marshall finally getting used to being split from Lily; we also had a brief glimpse that she's back in town. Tonight, Barney tries to find Marshall someone new to date.

"Heroes" debut, 8 p.m., NBC. Strange things are happening around the world. Different people — unrelated to and unaware of one another — have different powers. What's going on? This hour doesn't say, but it definitely has our attention. Its terrific young cast includes Santiago Cabrera ("Empire") as a guy who paints the future, Hayden Panettiere as an indestructible teen and Milo Ventimiglia as a guy who's convinced he can fly.

"Marie Antoinette," 9 p.m., PBS. Amid the power of the Austro-Hungarian Empire, Marie Antoinette's mother prepared her for a single-minded goal: Be pretty, be fun, marry a king and expand the empire. She went to France at 14, ill-prepared for harsh reality. David Grubin, a gifted producer-director, offers a vivid portrait of a bright spirit in the wrong place and time.