What we're watching: Snakes on a Plane debuts on HBO tonight, along with a new comedy special from Bob Saget. NASCAR Nextel Cup is racing under the lights at Bristol, and Saturday Night Live revisits the best of 2006-2007.

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): The Cat in the Hat (8 p.m.), Masters of Science Fiction (10 p.m.)

CBS (1080i): Ghost Whisperer (8 p.m.)

NBC (1080i): Medium (8 p.m.), Saturday Night Live (11:29 p.m.)

Fox (720p): N/A

CW (1080i): N/A

TNT-HD (1080i): Lord of the Rings: The Two Towers (8 p.m.), Remember the Titans (11:45 p.m.)

Discovery-HD (1080i): Sunrise Earth (7 p.m.), Living with the Kombai Tribe (8 & 11 p.m.), Becoming a Man in Siberia (9 p.m.), National Trust Gardens (10 p.m.)

ESPN-HD (720p): NASCAR Countdown (7 p.m.), NASCAR Nextel Cup at Bristol (8 p.m.), SportsCenter (11:30 p.m.)

ESPN2-HD (720p): N/A

Mojo HD (1080i): Beer Nutz (7 & 10:30 p.m.), Uncorked with Billy Merritt (7:30 p.m.), Three Sheets (8, 8:30, 9, 9:30 & 11:30 p.m.), Timeless (10 p.m.), Howard Stern (11 p.m.)

HDNet (1080i): Visual Effects Society Awards 2007 (7:30 p.m.), MLS: Wizards at Fire (8:30 p.m.), Nothing But Trailers (10:30 p.m.), The Hole (11 p.m.)

HDNet Movies (1080i): Frida (8:05 p.m.), Snatch (10:15 p.m.)

Universal HD (1080i): Surface (8 p.m.), Firefly (9 p.m.), Texas Chainsaw Massacre: The Next Generation (10 p.m.)

HBO-HD (1080i): Snakes on a Plane (8 p.m.), Bob Saget: That Ain't Right (10 p.m.)

Showtime-HD (1080i): Lord of War (7:10 p.m.), Man About Town (9:15 p.m.)

MAX-HD (1080i): Date Movie (8:30 p.m.), The Departed (10 p.m.)

STZ HD (1080i): Cars (7 p.m.), Pirates Of The Caribbean: Dead Man's Chest (10:45 p.m.)