Britney Spears BSpearsVitamin071307_4.jpg

Brit stopped at a drug store to buy some vitamins on Friday and the mob of photographers (including a few too many from Team X17!) documented her every move.

But X17 just might have the scoop! Listen to the music playing in Brit's convertible as she pulls out -- it sounds like our girl!

UPDATE! - Our source confirms it's Brit's very own music!