1. A system for distributing files and transmitting/receiving the distributed files, comprising: a file distribution/transmission/reception module depending upon an application program executable in a client computer and performed in a background process of a corresponding application program execution module, the file distribution/transmission/reception module receiving files designated on a host computer from a network and storing the received files while an application program is executed, or transmitting corresponding files to another client computer if the corresponding files exist, in response to another client computer's request for transmission of the files designated on the host computer.