Take it in to your local bike shop if you are really worried. The biggest factor in your chain's health (assuming you have kept it in a nice dry place over the years) is how much you ride it. It's a mechanical part, so it shouldn't simply go bad in an inert state. If you are riding it regularly though take it to your local shop and have it looked over. A new chain w/ installation should only run you about 20 or so bucks for a low end chain.