What would they think if you sang out of tune?

The Beatles are coming! The Beatles are coming!

It's been more than 45 years since the Fab Four first arrived in America, but on 09-09-09 - that's number nine, number nine, number nine to fans of the White Album - another invasion will be under way.

And this time, it's virtual. (And digital, too.)

On Wednesday, the best-loved pop group of all time will be reborn as computer-generated stars in the video game The Beatles: Rock Band, in which gamers will be able to make believe they are John, Paul, George, and Ringo by re-creating their music on plastic faux instruments and microphones.

On the same day, a severely wounded music industry will get a much-needed boost when the Beatles catalog - all 13 original British albums, from Please Please Me to Let It Be, plus a 14th, Past Masters - will be reissued in remastered, sonically upgraded form for the first time since the Liverpudlians' music came out on CD in 1987.

The marketing bonanza that will put Abbey Road and Rubber Soul on checkout counters at Starbucks and Whole Foods doesn't come at a time when the Beatles have fallen off the radar. To the contrary: Nearly four decades after their breakup, they remain as popular across the generations as ever.

"People scoff at the idea of a common culture," says Robert Levine, executive editor of Billboard magazine. "We live in a 100-channel world, and niches are everything.

"But music has always been a collective experience, a social experience. And along with the music that people listen to alone, there's the music that people listen to in a group, the music that everybody likes. We saw that when Michael Jackson died, with his music coming out of car windows as people drove down the street.

"And that's what you see with the Beatles, who have never really gone away."

Evidence of their music's being here, there, and everywhere is easy to find. Exhibit A was revealed by Billboard on Friday, when it unveiled the name of the top-selling CD of the decade, according to Nielsen SoundScan. Care to venture a guess? Something by Norah Jones, Britney Spears, or Eminem?

It's the Beatles' 1, the hit-singles collection released in 2000, which has moved a whopping 11.5 million copies this decade. (In overall sales, Eminem was first with 32 million sold, followed by the long-defunct Brits, with 28.2 million.)

A Pew Research Center poll of Americans' generational differences released last month demonstrated the Beatles' continued power as a unifying force among all ages. Asked for artists they "like a lot," respondents in all age groups - 16-29, 30-49, 50-64, and 65-plus - named the Beatles among their top four favorites, an unmatched feat.

(Michael Jackson was most popular with the young demographic and second among 30-49; Frank Sinatra led among seniors.)

Granted, it wasn't unanimous acclaim, though one has to wonder: Who are the 11 percent who said they dislike the Beatles, or the 4 percent who haven't heard of the creators of Sgt. Pepper's Lonely Hearts Club Band and "I Want To Hold Your Hand"?

The Beatles' decision to venture into the video-game world with Rock Band - made collectively by Paul McCartney, Ringo Starr, Yoko Ono, and George Harrison's widow, Olivia, with a nudge from their guitarist-gamer son, Dhani - is an effort to make a deeper connection with young and future fans.

"They all felt it would expose their music to new generations," Van Toffler, the president of MTV Networks Music Group - owner of Harmonix, which produces Rock Band - told USA Today. "The core audience who buys games are 12- to 34-year-old guys who probably don't own many Beatles albums."

On Rock Band, available for the PlayStation 3, Xbox 360, and Nintendo Wii, gamers follow the Beatles from their leather-jacketed early days at the Cavern in Liverpool to their last live concert, on the roof of the Apple Records building in January 1969.

With stops at The Ed Sullivan Show, Shea Stadium, and Abbey Road Studios (the last accompanied by psychedelic "dreamscapes"), players skilled at pressing the five guitar buttons or banging on an ersatz drum kit or singing in up-to-three-part harmony are doubly rewarded.

Competent performance lets a player progress chronologically through the game and unlock photo montages that tell the Beatles' story. There's lots of charming real-life chatter in the game, whose soundtrack was overseen by producer George Martin's son Giles, though you won't find a computer-generated John Lennon remarking, in 1966, that the Beatles are "bigger than Jesus."

But the more important, and fun, aspect of the game is that - as with other iterations of Rock Band and its more popular competitor, Guitar Hero - developing prowess on the instruments makes songs sound better. And it deepens a connection to the music by making gamers feel responsible for ensuring that George gets the guitar riff right on "Come Together" or that Ringo doesn't sing a bum note in "Octopus's Garden."

With this move, the Beatles have entered a lucrative adjunct of the music business. Rock Band, which has sold 7.7 million units, trails Guitar Hero, with 29 million copies sold. (Last week, Guitar Hero 5 was released, with songs by Santana, Nirvana, and Johnny Cash.) The music-video-game industry generated nearly $2 billion in 2008, up from $1.2 billion the prior year, according to NPD Group, a New York marketing firm.

This year, overall video-game sales are down 14 percent, says NPD's David Riley. "The industry goal as a whole is to increase the demographic and attract older fans," says Riley. "And this is a guarantee that, at the very least, you're going to pique interest at a time when the industry really needs it."

The music industry, meanwhile, is looking for a boost from more than sales of individual Beatles CDs and two box sets - one stereo, one mono.

In addition to the 45 songs on Rock Band, the songs on the Abbey Road album will be available for download for the game, at $1.99 each.

Acts from nerd-rockers Weezer to the English metal band DragonForce have seen skyrocketing sales of songs featured on Guitar Hero and Rock Band. "The next big thing in the music business is a lot of little things," says Billboard's Levine. "This is one of those things."

One of the big things Beatles fans have been awaiting is the release of digital versions of the songs on iTunes - and there have been hopes that such a deal could be announced soon.

But as long as Beatles albums sell as complete packages, there's little motivation to make them available piecemeal. (One rumor is that an iPod stocked with Beatles songs will be announced Wednesday.) "I wouldn't hold my breath," says Levine, noting that two of last year's biggest albums - AC/DC's Black Ice and Kid Rock's Rock N Roll Jesus - were not on iTunes, so fans had to buy them whole.

At Main Street Music in Manayunk, the used-CD section is full of Beatles titles. Owner Pat Feeney says fans are trading in Fab Four CDs in anticipation of buying the brighter, more vivid-sounding remastered versions.

"I'll bet every used bin across the country is full of Beatles catalog," he says. He has been frustrated trying to get the $260 mono box - he'd anticipated selling one or two, but fans preordered 10.

Fans have gotten used to not paying for recorded music, but the beleaguered industry is betting that people still consider a Beatles album a life-enriching purchase. "People know these albums, and they like these albums," says Levine. "If you don't think Rubber Soul is a good buy at $15, you must hate rainbows and puppies."