Forget that Jack Black wooed the fat-suit girl in “Shallow Hal.” What you need to know is, can the secret weapon of “High Fidelity” make a movie we’ll remember six seconds after the credits roll?

I’m mean, c’mon, is there a single Jack Black movie besides “Hi-Fi” you would pay to see twice?

Finally, there is because at long last he’s in a movie whose a) subject is Rock ‘n’ Roll; b) director is Richard Linklater (“Dazed & Confused”) and c) supporting cast includes a rockin’ bunch of kids who come within a drumstick’s width of upstaging him.

“School of Rock” stars Black as Dewey Finn, a loser guitarist who gets kicked out of his loser band and is about to lose his crash pad because his old pal who’s put up with no-rent-paying ways now has a gorgeous girlfriend who insists the time for a change is right now.

Ned, the roomate, doesn’t want to blow it with the Queen Bitch of the Universe, who is such a staple of Rock ‘n’ Roll lore — the girlfriend who spoils everything — that I’m surprised they didn’t name her Yoko. So he sides with bitch babe against poor Dewey, who immediately thinks the thing to do is start a new band — which will never happen because he’s totally lame and has the brain of a 10-year-old still living in the moment he first heard “Back in Black.”

But as the script has it, there are several musical 10-year-olds in his future who will prove he’s not such a loser after all, and that Rock ‘n’ Roll can save, well, their souls.

The magic of “School of Rock” is that it gets away with every teen-rock movie cliche from here to “Rock Around the Clock.” Do the kids defy adult authority? Sure. Does an evil meanie try to stand between them and rock destiny? Better believe it. Can a band of kids who have never played a bar chord before produce a catchy, rockin’ tune inside of three weeks? Why the hell not? It’s a movie, OK, and we’re doing this because we can, Linklater, Black and company are saying.

See, the people who made this flick understand that Rock ‘n’ Roll thrives in the heart of a child. “School of Rock” is about the mojo that made the girls go mad for the Beatles — the pure, ecstatic, raving fun of abandoning yourself to a rock tune. Black’s Dewey is a moron who has a doctorate in the Meaning of Rock ‘n’ Roll … it’s so basic that comes perfectly natural to a roomful of bright kids.

Combine this with a rockin’ score heavy on AC/DC and all the greatest hits from Classic Rock that Rocks radio and you’ve got a movie representing the gritty, nasty, silly and soaring firmament of Rock ‘n’ Roll That Matters (and where Huey Lewis, Billy Joel and Journey dare not dwell).

If that firmament matters to you, pony up the obscene ticket price (it’d be a crime not to see this in a theater) and get your butt in a seat. Better yet, if you’ve given up on Rock as hopelessly compromised by the mighty dollar, “School of Rock” might just get you believing again.