Famous classical song. Has a familiar tune...?

Question

It starts with "pr" and I have been looking for it for AGES.

Answer 1

Some Prelude, maybe?

If you can describe the song better, or at least where you heard it, that might help.

Even better, if you can hum or play a few bars into an mp3 file, so people can listen to it.

Answer 2

You say it's a famous, familiar piece... if so, it's probably featured here:

http://www.kickassclassical.com/most-pop...