Don’t know exactly what it is, but Judd Apatow has got it. And he should pass it along.

Apatow wrote and directed “The 40-Year-Old Virgin.” I thought the comedy was OK but was not one of it’s biggest fans; too often crass for the sake of being crass, and the film’s heart got lost in the darkness.

So I went into “Knocked Up” with low expectations - it’s written and directed by Apatow, too, and it’s just an eyelash under two hours.

I came out more pleased than I’ve felt in eons - or since I can remember, which is as much a commentary on my memory as on the quality of mainstream movies these days. (Mostly mediocre.)

Simply put: “Knocked Up” is not only a delightful comedy but it’s also a sweet family film (with husands and wives acting real, and children being too cute for it to matter), a funny commentary on pop culture, and a compassionate look at opposite ends of a continuum trying to meet in the middle.

Bottom line: It works.

I gave it 3 1/2 stars out of 4.

The story:

Seth Rogen, a “40-Year-Old Virgin” alum, plays a committed slacker: He lives in a house with four roommate who sit around smoking dope, playing Ping-Pong and talking about starting a Web site the focuses on breast shots in movies; they like doing the research, aren’t big on the work.

Katherine Heigl of “Grey’s Anatomy” plays a classy, babe-alicious producer for “E!” (Entertainment TV) who celebrates her new promotion to on-air talent by going to a nightclub with her pretty-but-edgy married sister _ played by “Virgin” alum Leslie Mann, a sexy comic talent the camera’s crazy about.

Heigl meets Rogen at the bar, they get blitzed, she takes him home and they have sex - but, due to a communication glitch, the booze and their screaming hormones, without protection.

The mismatched duo’s trying to make it work as boyfriend-girlfriend for the sake of the baby comprises the film’s soul.

Both recognize she’s stylish, he’s sloppy; she’s sophisticated, he’s comfortably raw; she’s straight, he’s a druggie; she’s confident, he’s not. As he says the first time he sees her naked, “You’re prettier than I am.”

But what drives the film is their awareness of their differences and the fact that both are frightened and don’t know what to expect. Yet they try.

It’s not easy because, in addition to the obvious, their only married role models are her passionate sister and the sister’s cooly ambivalent husband, played by Paul Rudd, the movie’s fourth “Virgin” alum - or fifth if you count Apatow.

Long-married with two kids, sis and her hubby are regularly at each other’s psyches. And, for Rogen, Heigl and the audience, it’s not a pretty picture.

But Aptow makes it all seem real, hope is never out of the frame for long, and the whole thing rings with the kind of authenticity you don’t expect from films riddled with long streams of crudity - films such as “Knocked” and “Virgin.”

Aptow tones down the graphic, epithet-laden dialogue that ran through “Virgin,” and, interestingly, the characters stand out more and their situations seem more immediate (although the Steve Carell-Catherine Keener scenes hit all the right notes in “Virgin.”

Aptow laces “Knocked Up” with similar consistently clever riffs and digressions, many of which take wonderful potshots at the culture.

Despite a few dead spots and scenes that run on too long, “Knocked Up” is a solid entertainment with a captivating story, solid performances, mostly excellent pacing and strong writing.

On a relationship level: The film shows how opposites can make it work if they stay honest, open and aware, try to accept the annoying differences, and are at the core truly nice - the right word - people.

Yes, besides being funny and satisfying, “Knocked Up” is an aww-shucks, feel-good movie - and a good choice for a date film.

Here we go again again.

If it’s summer 2007 - traditionally in movie land beginning Memorial Day weekend but actually beginning with the season’s first blockbuster release, “Spider-Man 3” - thus it’s time for another deluge of sequels sequels sequels.

This year’s deja vu all over again features twice last summer’s number: 14 vs. seven in 2006 - and only three in the heat of 2005.

That’s a big increase in do-overs - and an equally big decrease in new ideas and risk-taking.

Better to play it safe when millions and millions of dollars are at stake is the rationale.

Based on last year’s receipts, if they remake it, people will come - and more than once.

Each “franchise,” the operative word, comes with a built-in audience/fan base familiar with and appreciative of the characters and type of escapism; sequels have become the new comfort food.

Of course, some come with a proven track record that “suggests” the likelihood of getting your money’s worth.

Among these are the “Harry Potter” and “Bourne Identity” franchises, with “Shrek” and “Evan Almighty” good possibilities.

I saw “Shrek the Third” yesterday (Thursday night) and the story is thinner than its predecessors. Also, it more Muffin Man, less tacit-villain Prince Charming, but it’s still cute. Donkey tones down his act, and Fiona’s pregnant - meaning the ogres spent the time since “Shrek 2″ doing more than twiddling their green thumbs. All in all the animated movie’s OK froth; kids should love it.

“Evan Almighty” trades Steve Carrell for Jim Carrey and omnipotence for the task of playing a modern-day Noah and building an ark. Previews look amusing. And the escalating budget is rumored to make this the most expensive comedy ever. Worst-case scenario: “Heaven’s Gate.” Best case: And on the seventh day the audience was mightily entertained.

“28 Weeks Later” was a disappointment, especially because “28 Days Later,” its predecessor was so good, but the zombie-movie sequel had its moments.

Though “Pirates 2″ was a mess, “Pirates 3″ is pretty much a must-see anyway - for closure: Jack’s dead and gone? To the end of the world? Let’s rally octopus-face and the dead captain and go save him - after “Lost” is over.

Despite “Die Hard 3″ being the series’ weakest, enough years have passed to renew our faith, hopes and pleasant fantasies that Bruce Willis will deliver something closer to the first “Die Hard” - the quintessential action film.

I hold no hope for “Daddy Day Camp,” with - Fred Savage!? - instead of Eddie Murphy. Plus, the original was a misfire.

Steven Soderberg has admitted his regrets about making “Ocean’s Twelve” - and rightly so since it was thinner than notebook paper and as entertaining as watching Joan Rivers chat up celebrities on the red carpet. Soderberg says he’s got a new slant, perspective, whatever, on life, so “Ocean’s Thirteen” should be quality froth.

What else to look forward to, or not: “Rush Hour 3″ (Jackie Chan and Chris Tucker go to Paris); “Hostel 2″ (the torture and gore continue); “Fantastic Four: Rise of the Silver Surfer” (Jessica Alba says it’s got more meat; I’ll bite); “Mr. Bean’s Holiday” (not my cup of British tee-hee).

There’s also a “Halloween” remake remake.

Enjoy enjoy.

Zombies to the left of us, zombies to the right of us, zombies in front of us volleyed and thundered … and into the their midst rode throngs of horror-movie fans thirsting for more of the undead.

OK, that sounds kind of icky.

Yet there’s truth in it. If not, people would stop making zombie movies.

This year thus far: “Grindhouse,” “28 Weeks Later,” which opens today, the upcoming “Fido”‘ (a zombie comedy that’s the best of the lot), and even more on bargain-basement straight-to-DVD.

In the recent past: The “Resident Evil” films, the “Dawn of the Dead” and “Night of the Living Dead” remakes, “Land of the Dead” and the whimsical “Shaun of the Dead.”

Is there no end to the inhumanity?

Probably not.

The walking dead - or undead - or voodoo-created automatons - have lumbered across screens for decades.

Part of the allure: People know they’re not real.

Also: They look silly. Rember with the slow-moving old-school type, you could run circles around them, pick their pockets, stop to eat lunch as they approach without worrying about having time to get away; there was always time.

Only when they swarmed over you in packs were you meat.

In orther words, they were fun to watch.

And to think about: As I mention in my “28 Weeks Later” review (on insidebayarea.com/movies Friday), there’s a fast-zombie, slow-zombie debate on the Internet contrasting the traditional cinematic trudgers with the current Speed Racer crop.

One theory suggests they reflect the times, with the original George A. Romero trilogy (”Night of the Living Dead,” “Dawn of the Dead” and “Day of the Dead” reflecting the slower-paced ’60s-’80 and the more recent slew (excluding his 2005 entry, “Land of the Dead”) keeping pace with the video-game set.

I’m a traditionalist: I prefer the slow goers; if you’re already dead, what’s the hurry?

Another theory - my own - is since many zombie films use a virus to kill people, whose resurrected shells hunger for blood, brains or both, there’s an obvious connection to the ever-present threat of disease.

In the ’80s and ’90s, for instance, the resurgence in vampire films suggested parallels to the rise of the AIDS virus _ with blood being a factor in both, and there being a parallel between needles and teeth; also, the idea of immortality was a major lure, so a surge in spirituality also figured in.

Today, one of my colleagues thinks “28 Weeks Later,” with its military commander representing the government and committing insane and inane actions, reflects the current regime’s unconscionable initiating and doggedly continuing the onslaught in Iraq.

There’s also escalating paranoia about bird flu, biological warfare, and dreaded old standbys such as ebola.

Zombies can be reminders of the threat, although by being fantasy creatures, they offer perspective; and by moving as a snail’s pace, they let us laugh, providing a catharsis by showing us how easy they are to avoid.

I don’t have any insights into the cannibalism aspect other than: I imagine that once you’re dead, the thing you most hunger for is life.

And there’s probably a spiritual reminder buried in here, about grabbing life while you’re still a part of it, and how that’s the point of everything.

Your guess is probably as good as mine, if not better. (Don’t hesitate to share.)

Personally, I like the supernatural/horror mumbo-jumbo, because, knowing that it’s only a fantasy makes it super-conducive to escapism.

Especially when it’s done well. “28 Weeks Later” isn’t. But it’s predecessor, “28 Days Later” is, and it’s an excellent rush - if you like zombie movies.

If you want laughs, rent “Shaun of the Dead,” or wait for “Fido” to come out this summer; it’s like a combination of “Lassie,” “Far from Heaven” and an old-school zombie film. And I do not exaggerate.

It’s not unusual to have an actor exercise his vocal chops in a movie, or a TV series for that matter.

Bruce Willis did it in the old “Moonlighting” series, as did his co-star Cybill Shepherd. And they weren’t bad, even on the series’ soundtrack CD.

Mare Winningham has sung her share, even recorded an album.

Willis did, too; Don Johnson, also.

More recently, Joaquin Phoenix and Reese Witherspoon both showed well in the Johnny Cash biopic “Walk the Line.”

Eddie Murphy sounds great in “Dreamgirls” (out this week in DVD).

Now that I think of it, The “Mighty Wind” ensemble sounded pretty good.

Hugh Grant’s voice is decent in “Music and Lyrics,” an entertaining bit of fluff that’s out Tuesday on DVD.

Drew Barrymore doesn’t embarrass herself singing briefly in the same film.

It’s not like singing’s a requirement, or something every actor should try - Russell Crowe’s confining his to his band engagements is just fine.

But it’s the successes that come to mind, rather than the failures. (William Shatner is William Shatner is William Shatner.)

Barrymore sings again (sounds like a headline) in “Lucky You,” which opens today. I haven’t seen it so I can’t comment, but since the plot suggest her character’s voice is less than stellar, I imagine Barrymore can carry it off. (Let’s face it, she can do just about anything. And well.)

In “Spider-Man 3,” the inspiration for this riff, Kirsten Dunst sings - as Spidey’s sweetie Mary Jane - in a Broadway show and a jazz club.

In the film, which debuted opened last night and is only so-so, her voice gets panned in the press.

Actually, it’s not bad; it just lacks strength and range.

Dunst is much better in the small confines of the nightclub. Her voice has a sweet quality, something she can play with; i.e., find a phrasing that fits her style and range.

I figure, if Lee Marvin could carry off an entire number in the Clint Eastwood musical “Paint Your Wagon,” and sound convincing, that should give hope to everyone, not just actors.

And it should make it easier not to cringe everytime a movie ad shouts, “Such and Such Sings!”

Note to Steven Seagal, despite the aforemention “not to cringe” comment: Keep it off-screen.

Note to self: Keep it in the shower.