1. A method for servicing a client request for a streaming media (SM) object in a network having a content server which hosts SM objects for distribution over the network through a plurality of helper servers (HSs) to a plurality of clients, the SM object being comprised of a plurality of successive time-ordered chunks, the method comprising: receiving a request for at least a portion of an SM object at a local HS, the request including a playback starting time; determining whether or not the request can be satisfied by the local HS, the request being satisfied when a chunk having a starting time equal to the requested playback starting time resides on a disk associated with the local HS; determining whether there are any additional chunks on the local HS that follow the chunk that satisfies the request in consecutive time order; when it is determined that the request can be initially satisfied by the local HS, delivering to one of the plurality of clients the one or more chunks having an associated starting time equal to the requested playback starting time from the local HS and updating the playback starting time when the end of the SM object has not been reached after delivery; when it is determined that the request cannot be satisfied or continue to be satisfied by the local HS, identifying a server in the network that is not the content server storing at least a predetermined M chunks having a starting time equal to one of the requested playback starting time, when the request cannot be initially satisfied by the local HS, or the updated playback starting time, when the request cannot continue to be satisfied by the local HS, according to a minimum normalized cost function; delivering to the one of the plurality of clients the identified M chunks and updating the playback starting time when the end of the SM object has not been reached; when it is determined that the request cannot be satisfied or continue to be satisfied by the local HS or remote HS in the network that is not the content server, delivering to one of the plurality of clients the one or more chunks from the content server the one or more chunks having an associated starting time equal to the requested playback starting time or the updated playback starting time until it is determined that the local HS or remote HS can satisfy the request or until the end of the SM object has been reached, whichever comes first, and updating the playback starting time when the end of the SM object has not been reached; and when requests are not satisfied by the local HS, receiving the chunks from the identified server at the local HS until it is determined that a next chunk to be retrieved is stored at the local HS.