1. A method for retrieving specified content in a peer-to-peer network, the method comprising: checking the availability of specified content from content sources including other clients and content servers in the peer-to-peer network, wherein the availability of the specified content is identified in a list including names, the list provided to clients in the peer-to-peer network, and wherein the list including names is periodically updated to reflect a current availability of content from the content sources; and retrieving the specified content in parallel from a combination of clients, servers, or clients and servers, wherein the specified content is retrieved from: one or more of the other clients in the peer-to-peer network when the specified content is available from one or more of the other clients in the peer-to-peer network as identified by the list including names, one or more of the content servers in the peer-to-peer network when the specified content is not identified on the list including names, and one or more of the content servers in the peer-to-peer network when a guaranteed delivery time of the specified content is not satisfied by the other clients in the peer-to-peer network.