What is the name of a Symphony Orchestra piece?

I have had this tune in my head from a well known piece from a symphony orchestra. I'm not sure if it is in Mozart or Betoven or one of the other compositions. If you can understand, the tune or beat goes something like this: Da Da Da Da!.........Da Da Da Da!........Da Da Da.. Da....Da.....Da. Thanks a lot I want to download it before my birthday this month. I got my first MP3 for Christmas. But I refuse to pay 99c per song. Sorry went off on a tangent there. Just focus on my question. Thanks.