JOINT FILING AGREEMENT

 
                             JOINT FILING AGREEMENT

         We, the signatories of the statement on Schedule 13D to which this
Agreement is attached, hereby agree that such statement is, and any amendments
thereto filed by any of us will be, filed on behalf of each of us.

Dated: May 19, 1999



                                     GENERAL ELECTRIC COMPANY


                                     By:   /s/ Xxxx X. Xxxxx
                                         --------------------------
                                         Name:  Xxxx X. Xxxxx
                                         Title: Vice President


                                     NATIONAL BROADCASTING HOLDING COMPANY, INC.


                                     By:    /s/ Xxxx X. Xxxxx
                                         --------------------------
                                         Name:  Xxxx X. Xxxxx
                                         Title: Treasurer


                                     NATIONAL BROADCASTING COMPANY HOLDING, INC.


                                     By:   /s/ Xxxx X. Xxxxx    
                                         --------------------------
                                         Name:  Xxxx X. Xxxxx
                                         Title: Executive Vice President