Royalty Free Classical Music

Hi there,

Im a video editor and am about to produce a high concept, high impact short show-reel for the company I work for.

Now music is obviously vitally important for this, I have heard that if a composer has been dead for a certain amount of years I can use there music without getting into trouble with copyright people, is this true?

Really I would like to use some Kings of Leon but know there would be plenty of red tape so instead might try and go for some Wagner, Bach or Mozart.

Thanks for your help in advance