This first weekend of television sweeps month has a real old-fashioned feel about it. In the old days, before reality television, networks used to try to attract viewers with blockbuster movies, star-studded cast reunions, gimmicky crossover episodes and holiday specials. And that’s exactly what’s happening Sunday.

The WB network takes the most conservative approach to sweeps, pre-empting its entire Sunday and Monday night schedules to broadcast the 2001 epic “The Lord of the Rings: The Fellowship of the Ring” (7 p.m. Sunday, WB). The question remains how many people have already seen this film in the theater, on cable or on DVD.

CBS offers a blast from its past with “Dallas Reunion: Return to Southfork” (8 p.m. Sunday, CBS). Long before “Desperate Housewives,” this oil-patch potboiler attracted tens of millions of viewers to its prime-time soap-operatics. Original cast members, including Larry Hagman, Victoria Principal, Linda Gray, Patrick Duffy, Charlene Tilton, Ken Kercheval and Steve Kanaly, will be on hand to reminisce.

NBC hopes that the combination of two dramas will multiply viewers. “Las Vegas” characters Sam (Vanessa Marcil), Danny (Josh Duhamel) and Ed (James Caan) show up in the Boston morgue on “Crossing Jordan” (9 p.m. Sunday, NBC), along with a deceased high-roller with a briefcase containing $3 million handcuffed to his wrist. The storyline continues Monday when “Jordan” star Jill Hennessey appears on “Las Vegas.”

Tonight’s highlights

• Dierks Bentley is host of “40 Greatest Road Songs” (7 p.m., CMT), a countdown of country highway tunes.
• Scheduled on “48 Hours Mystery” (9 p.m., CBS): A woman shoots her husband. Self-defense or murder?

Sunday’s other highlights

• Scheduled on “60 Minutes” (6 p.m., CBS): profiles of SpaceShipOne rocket builder Burt Ruttan and motivational speaker Dave Ramsey, who preaches about the perils of personal debt.
• Scheduled on “Dateline” (6 p.m., NBC): cleanliness issues in school cafeterias.
• Police seize George’s twin brother on the second-season premiere of “Arrested Development” (7:30 p.m., Fox).
• Ray Winstone and Helena Bonham Carter star in “Henry VIII” on “Masterpiece Theatre” (8 p.m., PBS, concludes next Sunday).
• Jennifer Connelly appears on “Inside the Actor’s Studio” (8 p.m., Bravo).