It's always something of a head-scratcher when old shows that were influential favorites take years to make the digital jump to DVD. But finally Bill Cosby and Kermit the Frog -- two kings of very different sorts of comedies -- are back to delight another generation of fans.

"The Cosby Show: Season 1" (Ventura, four-disc DVD $49.99, not rated, available now) Little needs to be said about the success of Bill Cosby's iconic sitcom, which ran from 1984 to 1992. The adventures of Cliff, Clair, Sondra, Denise, Theo, Vanessa and Rudy set a standard for prime-time family comedies that stands to this day.

Even early on, the show's formula worked. The first season's 24 episodes show the Huxtables overcoming crises with humor and love. It's funny fare for the whole family.

As a nice treat, the DVD's fourth disc includes the 90-minute feature "The Cosby Show: A Look Back Special." Cast and crew interviews plus celebrity guest appearances capture the show's nostalgia. Deleted scenes, bloopers and audition footage all provide a glimpse into what life was like on the set of the top-rated sitcom.

"The Muppet Show: Season 1" (Buena Vista Home Video, four-disc DVD $39.99, not rated, available Tuesday) Jim Henson's wry take on TV variety shows debuted in 1976 and ran until 1981, showcasing the efforts of Kermit the Frog to put on his own successful production each week. Making Kermit's life a challenge was a cast of troublemakers, including Miss Piggy (his smothering romantic interest), the unfunny comic Fozzy Bear and an odd little creature called Gonzo. "The Muppet Show's" humor was equal parts parody, wordplay and sight gag.

Using foam and fake fur, the puppeteers managed to create lasting characters, a rarity even on the variety shows Henson's program lampooned.

Though "The Muppet Show" first aired nearly three decades ago, it hardly seems dated. The show's age is apparent primarily thanks to its celebrity guest roster, which included Ruth Buzzi, Rita Moreno, Florence Henderson, Peter Ustinov, Phyllis Diller and Twiggy. For those not old enough to remember the show during its original run, the DVD offers a crutch: An optional feature flashes fun facts about the guest stars and the Muppets on the screen as you watch. (An example: The name of Muppet performer Frank Oz is short for Frank Oznowicz.) Additionally, the set offers a promo gag reel, the original pilot and Henson's original pitch for the show.

New on DVD:

Saved by the Bell: Season 5 (Lions Gate Home Video: three-disc DVD $29.98; not rated; available now) The adventures of Zack, Mr. Belding and the gang -- including the infamous Zack-Slater melee -- continue during senior year at Bayside. Extras include a "making of the series" documentary.

Because of Winn-Dixie (Fox Home Entertainment: DVD $29.98; PG; available Tuesday) A young girl's lonely life takes a turn for the better when she adopts a Picardy shepherd dog she finds in the local supermarket. Extras include commentary by stars Jeff Daniels and AnnaSophia Robb and producer Trevor Albert; a gag reel; a behind-the-scenes featurette; and "Diamond in the Ruff," a dog-training featurette.