1. A system for controlling use of requested digital content having usage rights associated therewith, said system comprising: a client computer having a standard application program including a standard rendering engine programmed to render content; a communications interface for coupling said client to a server having digital content stored thereon; and a client side security module, separate from the standard rendering engine, which is downloaded and included in said client computer, the security module being programmed to be attached to the standard application program, to enforce usage rights for which the standard rendering engine is not programmed to enforce, and to provide access to the standard rendering engine, wherein, in response to a request to render the requested digital content, the security module determines whether the requested digital content is protected content based upon the usage rights associated with the requested digital content, and wherein, when the requested digital content is protected content, the security module intercepts a request to the standard rendering engine to render the protected digital content, and wherein, when the security module determines that the requested digital content is protected content, the security module determines whether to allow a user to perform a requested function on the protected digital content based upon the usage rights associated with the protected digital content, and responds to the request to perform the requested function on the protected digital content based on the usage rights associated with the protected digital content, and wherein, when the security module determines that the requested digital content is not protected content, the security module disengages from the standard rendering engine.