What we're watching: It's a big Saturday night, with the start of the NBA Playoffs, a NASCAR Nextel Cup Race from Phoenix, The Fast and the Furious: Tokyo Drift on HBO and Thank You For Smoking on Cinemax, but we'll stick with a new Saturday Night Live featuring Scarlett Johansson.

Our traditional high-def listings continue below.
Here are some other HDTV programs showing on selected networks today. All times are Eastern and reruns are in italics, premieres in bold:

ABC (720p): Harry Potter and the Sorcerer's Stone (8 p.m.)

CBS (1080i): NCIS (8 p.m.), CSI: NY (9 p.m.)

NBC (1080i): Heroes (8, 9 & 10 p.m.), Saturday Night Live: Scarlett Johanssen (11:29 p.m.)

Fox (720p): NASCAR: Phoenix 500 (8 p.m.)

CW (1080i): N/A

TNT-HD (1080i): Exit Wounds (6 & 11 p.m.), Walking Tall (8 & 9:30 p.m.)

Discovery-HD (1080i): Sunrise Earth (7 p.m.), Destination HD (8 & 11 p.m.), The Once and Future City: Los Angeles (9 p.m.), We Built This City (10 p.m.)

ESPN-HD (720p): SportsCenter (6 & 11 p.m.), NBA: Magic vs. Pistons (7 p.m.), NBA: Jazz vs. Rockets (9:30 p.m.)

ESPN2-HD (720p): 2007 Jordan Brand All-American Classic - Yellow vs. Royal (9 p.m.), SportsCenter (11 p.m.), Baseball Tonight (11:30 p.m.)

INHD (1080i): Beer Nutz (7 p.m.), Uncorked with Billy Merritt (7:30 & 10:30 p.m.), Gotham Boxing (8 p.m.), Dr. Danger (10 p.m.), Howard Stern (11 p.m.), Three Sheets (11:30 p.m.)

HDNet (1080i): True Music w/ Katie Daryl (7 p.m.), InFocus (7:30 p.m.), MLS: Wizards at Fire (8:30 p.m.), Nothing But Trailers (10:30 p.m.), Indiana University's Little 500 2007: Men's Race (11 p.m.)

HDNet Movies (1080i): Sidewalks of New York (6:15 p.m.), What Planet Are You From? (8:15 & 11:45 p.m.), Bob Roberts (10 p.m.)

Universal HD (1080i): The Night of the Living Dead (6:30 p.m.), Surface (8 p.m.), Battlestar Galactica (9 p.m.), Mary Shelley's Frankenstein (10 p.m.)

HBO-HD (1080i): The Big Bounce (6:30 p.m.), The Fast and the Furious: Tokyo Drift (8 p.m.), The Sopranos (10 p.m.)

Showtime-HD (1080i): The Tudors (8, 9 & 10 p.m.), Debbie Does Dallas Again (11:30 p.m.)

MAX-HD (1080i): Date Movie (6:35 p.m.), Roll Bounce (8 p.m.), Thank You For Smoking (10 p.m.)

STZ HD (1080i): Find Me Guilty (9 p.m.), The Benchwarmers (11:10 p.m.)