Page 19 of 20 EXHIBIT A --------- Agreement of Joint Filing ------------------------- The undersigned hereby agree that a single Schedule 13G (or any amendment thereto) relating to the Common Stock of Support.com, Inc. shall be filed on behalf of each...

                                                                   Page 19 of 20
                                   EXHIBIT A
                                   ---------

                           Agreement of Joint Filing
                           -------------------------

          The undersigned hereby agree that a single Schedule 13G (or any
amendment thereto) relating to the Common Stock of Xxxxxxx.xxx, Inc. shall be
filed on behalf of each of the undersigned and that this Agreement shall be
filed as an exhibit to such Schedule 13G.

Date:  February 14, 2001


                                                              
Entities:       Accel VI L.P.
                Accel VI Associates L.L.C.
                Accel Internet Fund II L.P.
                Accel Internet Fund II Associates L.L.C.
                Accel Keiretsu VI L.P.
                Accel Keiretsu VI Associates L.L.C.
                Accel Investors '98 L.P.
                                                                   By:  /s/ X. Xxxxxx Sednaoui
                                                                      -------------------------
                                                                         X. Xxxxxx Sednaoui,
                                                                         Attorney-in-fact for the
                                                                         above-listed entities

Individuals:    Xxxxx X. Xxxxxx
                Xxxxxx X. Xxxxxxxxx
                X. Xxxxxx Sednaoui
                Xxxxx X. Xxxxxx
                J. Xxxxx Xxxxxx                                    By:  /s/ X. Xxxxxx Sednaoui
                                                                      -------------------------
                                                                         X. Xxxxxx Sednaoui,
                                                                         Attorney-in-fact for the
                                                                         above-listed individuals