If you don't know — or don't want to know — the so-called secrets of "The Da Vinci Code" before it opens in theaters, you'll want to stay out of the DVD section. There are at least 20 discs that purport to sort fact from fiction in Dan Brown's best-seller.

As might be expected, most of them have an agenda, or at least a decided point of view, so many seekers may find themselves choosing by brand.

On that basis, National Geographic's "Is It Real? Da Vinci's Code" (3 stars, National Geographic, $14.98), might be the most even-handed. It premiered last month on the magazine's cable channel as an episode of a series ostensibly devoted to getting to the bottom of mysteries as diverse as Bigfoot and sleepwalking.

Veteran narrator Will Lyman reports that a National Geographic-sponsored survey revealed that 32 percent of readers believe that the theories used by Brown in the novel are fact, and the show's producers set out to examine the primary ones, including whether Da Vinci and other artists embedded messages in their art.

It also invites experts to debate the motives of the Knights Templar and the existence of an alleged brotherhood known as the Priory of Scion.

"Beyond the Da Vinci Code" (2 stars, A&E, $19.95) was produced for the History Channel, and it hopes to make us raise our eyebrows in skepticism of the official story.

While offering arguments on both sides of the debate, the show gives more time to researchers like Richard Leigh, who believes the relationship between Jesus of Nazareth and Mary Magdalene was something more than savior and sinner.

Leigh unsuccessfully sued Brown for ripping off "Holy Blood, Holy Grail," a nonfiction book he co-wrote. And though he takes issue with some of the other theories that Brown recycles, a casual viewer would conclude there was something to all this.

Stark contrast is provided by "The Real Da Vinci Code" (3 stars, Acorn Media, $14.99), produced for England's Channel Four and shown here on the Discovery Channel.

This one is rather cheekily narrated by Tony Robinson. It takes us through the plot points of the novel and the claims Brown has made to support them, and makes them sound, well, fairly ridiculous.

First aired before the recent "60 Minutes" segment that reached similar conclusions, it dismisses the whole Priory of Scion business and the related secret dossier as a fraud.

ALSO OUT THIS WEEK:

DVD buyers who attend movies are learning to control the impulse to buy a favorite film as soon as it is released. If you wait a few months, you'll be rewarded with the inevitable special edition with all the goodies that lure so many people into buying the same film twice.

The latest victims are "Napoleon Dynamite" cultists, who now have to own "Like, the Best Special Edition Ever!" (2 stars, Fox, $26.98) version of the low-budget 2004 comedy about, well, really stupid people in Utah doing and saying weird stuff.

Classified as one of those films people love or hate (I'm in the latter camp; the DVD's extra ratings star is for its undeniable effort to please the faithful), the original movie is an afterthought to this loaded two-disc set, which includes commentary by director Jared Hess, star Jon Heder and producer Jeremy Coon, about seven minutes of cut footage and an extensive on-set documentary.

FAMILY PICK OF THE WEEK:

"Duma" (3 stars, Warner, $19.98): Carroll Ballard is responsible for some of the most beautifully made and beautifully told family films of our time, including "The Black Stallion." This story is about 12-year-old South African Xan (Alex Michahetos), who rescues a cheetah cub he and his father (Campbell Scott) find near the family farm. When the family moves to the city, Xan makes it his mission to return the animal to the wild.

"Duma" is in the best Ballard tradition, which is to say that although parents may rent or buy it for their kids, they'll be transfixed by it, too. It's available in both wide-screen and full-screen versions, so be sure to check the box. This film begs to be seen the way its director envisioned it.