A Rugrats Kwanzaa (6:30 p.m., Nickelodeon): Aunt T. teaches the babies a thing or two about this holiday celebration in this new animated special.

JAG (7 p.m., Ch. 2): Harm has to look after a difficult young petty officer who's charged with a crime shortly before Christmas.

Nova (7 p.m., Ch. 7): The life of the world's oldest living organism — 4,644-year-old bristlecone pine nicknamed Methuselah in California's White mountains.

That '70s Show (7 p.m., Ch. 13): Hyde brings his girlfriend along on "guys' night out."

Buffy the Vampire Slayer (7 p.m., Ch. 24): One of the series' best-ever episodes — the largely silent "Hush" — is repeated.

Gilmore Girls (7 p.m., Ch. 30): Lorelai and Sookie throw an unexpectedly lavish Christmas bash at the inn for their families.

Jane Doe (7 p.m., USA): Teri Hatcher and Rob Lowe star in this dumb, predictable, unthrilling "thriller" about kidnapping and assassination plots all tied up in one messy bundle.

Undeclared (7:30 p.m., Ch. 13): In the first of a very funny, all-too-real two-parter, Steven opts to join a fraternity.

The Guardian (8 p.m., Ch. 2): Nick gets a new boss (new cast member Wendy Moniz), a new job offer and a tough case involving anti-Arab bias.

NYPD Blue (8 p.m., Ch. 4): McDowell meets the daughter she gave up for adoption when she arrests the girl.

Frasier (8 p.m., Ch. 5): The only thing worse for Martin than his difficult boss is Frasier's attempt to mediate the situation.

24 (8 p.m., Ch. 13): Kimberly is handed over to her kidnappers' employer.

Smallville (8 p.m., Ch. 30): Clark begins to understand the danger Kryptonite poses for both him and the rest of Smallville when one of his father's former farmhands shows up showing some strange side-effects.

Scrubs (8:30 p.m., Ch. 5): A strange, somewhat sad Christmas is complicated for J.D. when Dr. Cox's ex-wife suddenly reappears at the hospital.

Judging Amy (9 p.m., Ch. 2): Amy gets a tough question from her daughter and a tough judge looking over her shoulder.

Dateline (9 p.m., Ch. 5): A report on troubled comedian Paula Poundstone.