Unfortunately, 25 years is incorrect. The original copyright laws let the creator of a work have a copyright for 28 years. Over the past century Congress has expanded the length of time that a copyright is held. The current length of time is the life of the creator plus 70 years. Works for hire or anonymous works are protected for 95 or 120 years. All this is retroactive to all works that were still under copyright when the law was passed.
http://http://www.copyright.gov/circs/circ1.html
This is the reason that "Happy Birthday" is still copyright. Probably any recording you have is still copyright. It's just silly.
Ryan