Give Britney Spears credit . . . but not very much. At Constitution Hall last night, the 17-year-old retired Mouseketeer and diva-in-waiting delivered a short but vigorous show in which aerobic choreography trumped musicianship at every turn.

Part of the problem was that the sound mix in Constitution Hall was abysmal, particularly the overmiked drums that transformed Spears's few attempted ballads, including "From the Bottom of My Broken Heart" and "I Will Be There," into shrill harangues. Another ballad, "Born to Make You Happy," even tossed in a gratuitous Latin disco dance interlude.

The rhythm of this particular night, however, was decidedly uptempo, from the opening "(You Drive Me) Crazy" to the closing duo of "Sometimes" and ". . . Baby, One More Time." The latter is the monster single that's driven Spears's debut album past quadruple platinum (and so what if the beat is wholly recycled from 'N Sync and Backstreet Boys, albeit by the same songwriters?).

The hour-long show started off with a mock schoolroom scenario inspired by "Grease" or "Bye Bye Birdie," with Spears establishing the precision choreography that dominated the evening. However, "Soda Pop," Spears's actual attempt at a "Macarena"-style dance anthem, simply fizzled flat.

With only one album and two hit singles setting up her first-ever headlining tour, Spears had to rely on covers to fill out the program. In fact, all too much of last night's show was spent on uninspired homages to more talented divas such as Madonna ("Material Girl," including a stiff re-creation of the video), Janet Jackson ("Black Cat," "Nasty Boys") and Cher ("The Beat Goes On"). This portion of the program felt like one of those high school talent shows in which students re-create hit singles--only the production values were higher.

For some reason, Spears also covered Journey's "Open Arms."

For much of the concert, it appeared that Spears was lip-syncing with a live microphone, which allowed her to ad-lib and philosophize with a little bit of security on the musical front. In any case, her own focus seemed less on the singing than on the dancing, along with several crucial costume changes. Spears is an energetic performer, but her dance moves exhibit the stiffness and razor-sharp cleanness of someone who is premeditating every move, rather than letting it flow. Should this music career fizzle, she has a great future as an aerobics instructor.

The first half of the concert resembled an amateur hour. First up, and down, was 3rd Storee, a very young R&B quartet, "13 to 17--hot, young and single" boys, the emcee noted. They have time to improve and get married. That group was followed by Michael Fredo, a Tommy Hilfiger model whose musical career ended the moment he opened his mouth to sing "Do You Think About Me?" (The answer: not anymore). Last, and least, came Boyz-N-Girlz, an inflatable dance-pop quartet that is unlikely to be heard from again. All three acts performed to prerecorded tracks in front of a huge TOMMY JEANS banner. Clearly, every expense was spared in this portion of the concert.

CAPTION: Britney Spears stretched her aerobic, if not vocal, limits.

CAPTION: Britney Spears and Co. work up a sweat at Constitution Hall.