Saturday
Horse racing (3 p.m., Ch. 5): The Preakness
NBA playoffs: Heat at Pacers (6 p.m., TNT); Spurs at Lakers (8:30 p.m., TNT)
Harry Potter and the Sorcerer's Stone (7 p.m., Ch. 4): ABC airs this for the second time in six days.
28 Days Later (9 p.m., HBO): Scary and really gory 2002 horror flick. (Rated R)
Sunday
NBA playoffs: Timberwolves at Kings (1:30 p.m., Ch. 4); Pistons at Nets (6 p.m., TNT)
The True Story of Troy (6 p.m., History): Well, as true as possible, given that Troy was destroyed thousands of years ago.
King of the Hill (6:30 p.m., Ch. 13): Kahn gives up and embraces the redneck lifestyle.
Helter Skelter (7 p.m., Ch. 2): Three-hour TV movie that recounts how Charles Manson was able to persuade others to commit murders for him.
Extreme Makeover: Home Edition (7 p.m., Ch. 4): Rebuilding a home infested with potentially deadly mold.
The Simpsons (7 p.m., Ch. 13): Bart and the rest of the family are deemed un-American.
Charmed (7 p.m., Ch. 30): Leo is sucked into an evil universe.
Las Vegas Live (7 p.m., Bravo): A look at the who/what/where/when of the gambling mecca.
Super Millionaire (8 p.m., Ch. 4): Regis Philbin kicks off another five-day run for this $10 million version of the game.
Law & Order: CI (8 p.m., Ch. 5): Somebody is killing elderly patients.
The Practice (9 p.m., Ch. 4): Bobby Donnell (Dylan McDermott) returns as the firm breaks up and the series ends.
Crossing Jordan (9 p.m., Ch. 5): Jordan and Devan disagree again.
The Sopranos (10 p.m., HBO): Tony is obsessed with an old flame.