She didn’t buy the ring, but she certainly could have afforded it. Last month Spears’s album, “”… Baby One More Time,’’ debuted at No. 1, and it’s still there five weeks later. The first single, the title track, is double platinum, and her video is in heavy rotation on MTV. Spears got her big break at the age of 11 when she joined the new ““Mickey Mouse Club,’’ which featured two kids who became part of ‘N Sync (as well as ““Felicity’’ star Keri Russell). Filmed in Orlando, the show later led Spears to ‘N Sync’s manager Jonny Wright. She landed a solo deal at Jive Records, but built her massive teen-fan base as the opening act for ‘N Sync. Spears has managed to capitalize on two trends at once. She has the same cool, sexy style as such bubble-gum-pop groups as the Backstreet Boys. But she’s also a teenage girl singing about love, in the mold of R&B singers Brandy and Monica. ““Her music is catchy, it’s hip-hop,’’ says Brittany Oster, a 12-year-old fan. ““You can dance to it.’’

Spears has always been ambitious. Growing up in Kentwood, La. (population: 2,500), the daughter of a schoolteacher, she began propelling herself toward stardom when she was 4. She started with dancing lessons and local recitals; at 8 she took up gymnastics, and attended Bela Karolyi’s training camp. She’s treated like a normal girl at home, but a recent MTV appearance in New York was a different story. Teenage girls mimicked the naughty Catholic-school uniform she wears in the video for “”. . . Baby One More Time’’: unbuttoned white shirt, sexy black bra and a gray miniskirt hiked so high it makes Ally McBeal look like a nun. Though it was wintry cold, teenage boys took off their shirts and wrote love letters to her in greasepaint on their chests. ““Will you go to the prom with me?’’ they pleaded. And, ““I love you, Britney.’’ ““It was really crazy,’’ she says.

This is not to say that Spears herself isn’t starstruck. In Los Angeles, she makes daily visits to the Coffee Bean ““because every time we go, we see somebody famous.’’ Like who? ““I saw the guy from “Tommy Boy’.’’ David Spade? ““Yes! Yes!’’ Spears screeches. ““He was just standing there and drinking coffee. It was weird.’’ But the guy Spears is really looking to share a cup of joe with is ““Ben Affleck. He’s so cute. And he doesn’t have a girlfriend, now, does he?’’ She looks off dreamily. Britney Spears doesn’t just play a teenager on MTV. She really is just 17.