YOU CAN TELL winter is on its way because George Winston's "December" CD is back on the Billboard charts -- since its release in 1982, "December" has reappeared annually just before the first frost.

That album of starkly atmospheric solo piano has sold more than two million copies, making it the all-time best-seller on Windham Hill, a record label that with its haunting, mostly acoustic-instrumental music, distinctive graphics and almost fanatical attention to quality became intimately identified with that vague music/lifestyle moniker "New Age." "Windham Hill" became a buzzword itself, too often used by critics looking for an easy way to dismiss this new outpouring of soothing, delicate music.

Not that being dubbed New Age really hurt Windham Hill fortunes much. In 15 years, the company has evolved from a three-person living-room cottage industry to a 55-employee, $30 million-a-year corporation that has released 150 impeccably performed and produced albums (including 12 of their famous samplers). Windham Hill is celebrating the occasion with "The First Ten Years," a two-disc compilation of more than 170 minutes of its unmistakable music from the label's formative first decade.

Several Windham Hill artists appear in the area this week, including solo pianist Liz Story, husband-and-wife guitar and vocal duo Tuck & Patti; and folksinger-songwriter Cliff Eberhardt, one of the label's most recent signings and a harbinger of new direction. And at a time when Windham Hill is making aggressive moves toward expanding and diversifying its artist roster, moving from soft-focus instrumentals into edgier pop, jazz and vocal turf, the label's artists themselves want to dispel the notion that everything on the label sounds alike. It's a lingering misconception that really burns the Hill people up.

"There has been a lot of sort of New Age-bashing, although I think with a lot of our new releases we've managed to sort of dodge that," says Will Ackerman, the 41-year-old guitarist who founded the company and its unique recording style when he recorded an album his own solo acoustic compositions at the insistence of friends.

"Windham Hill was this marvelous little experiment that began modestly and turned into this mega-thing which people associated with a term that I always hated -- New Age," Ackerman says. And I think there was also sort of a yuppie thing, too -- yuppie-baiting began to happen. So suddenly the counterculture thing that Windham Hill was had moved to some sort of center. Articles were written which more or less made us sound like some sly and very cynical marketing ploy. And to think of the innocence with which this all began, and the naivete that was our only weapon."

In 1975, California carpenter Ackerman borrowed five bucks each from 60 "investors" to make a pristinely recorded album of his own meditative, pastoral solo acoustic guitar. The anniversary compilation opens with Ackerman's "The Bricklayer's Beautiful Daughter" from that first album, "In Search of the Turtle's Navel."

"When we chose the tracks for this compilation, we tried to go more or less chronologically," Ackerman says. "But the pieces that were picked obviously were my sentimental favorites and {executive producer} Dawn Atkinson's favorites. Basically, this music moves me. It works. And it was pretty amazing to look at it all -- all that history came flooding back."

One of the label's early discoveries, pianist Liz Story actually left Windham Hill for a two-album stint with RCA's Novus jazz label. But Story recently returned to the warm embrace of her first home with her latest solo piano collection "Escape of the Circus Ponies," which she co-produced with old pal Ackerman. Story's lyrical "Bradley's Dream" is included on the label's anniversary compilation, in part because it was the first note of Story's music Ackerman heard.

The short Story story: "I had made a tape and sort of forgotten about it. One day I played it for a friend, and she suggested that I send it to Windham Hill. Now, I hadn't heard of them, and they weren't getting any radio play at the time."

Ackerman called her four days later, signed her, and with her album "Solid Colors," Story became known as the "queen of New Age," a dubious honorific she shrugs off today. On her new album Story says she both improvised and notated her intimate music, which may sounds like a contradiction but is borne out in the listening.

"It's becoming more and more a dance with the piano," Story says. "It's being both the choreographer and the dancer."

Cliff Eberhardt, one of Windham Hill's most recent signings, has been on the singer-songwriter scene for years, but it took him a long time to find the right record label, and vice versa. "After the frustration I'd had in the music business for years, I wanted a label that wasn't going to use me for a quick hit, that wanted to develop me as an artist," he says.

But like many others, Eberhardt had preconceptions about the label. "Oh, yeah!" he says, cracking up. "People say 'Oh -- Windham Hill,' and then they think that you're gonna do just guitar solos all night, with windchimes in the background. {Folksinger} Christine Lavin told me 'Windham Hill is really interested in recording you,' and I went 'What? You must have the wrong person!' "

Eberhardt says he was always respectful of the product Windham Hill put out. "It was a classy label. . . . Everybody in that company just about is a musician or an ex-musician. So they understand music, which is something that most record industry people have not remembered -- that we are buying this product because it's music, and it gives us pleasure to listen to."

LIZ STORY -- Appearing Monday at Blues Alley.

CLIFF EBERHARDT -- Appearing Wednesday with Richie Havens at the Barns of Wolf Trap.

TUCK & PATTI -- Appearing Wednesday at the Birchmere.