WPG SOFTWARE FUND, L.P

   1
                                                                       EXHIBIT A
                                                                 to SCHEDULE 13D
                             JOINT FILING AGREEMENT

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

Dated:  January 8, 2001
                                    XXXXX, XXXX & XXXXX, LLC

                                    By:     /s/  Xxxxxxxx X. Xxxxxx
                                            -----------------------------
                                            Name:  Xxxxxxxx X. Xxxxxx
                                            Title: Managing Director

                                    WPG SOFTWARE FUND, L.P

                                    By:     XXXXX, XXXX & XXXXX, LLC
                                            its General Partner

                                    By:     /s/  Xxxxxxxx X. Xxxxxx
                                            -----------------------------
                                            Name: Xxxxxxxx X. Xxxxxx
                                            Title:  Managing Director

                                    WPG RAYTHEON SOFTWARE FUND, L.P

                                    By:     XXXXX, XXXX & XXXXX, LLC
                                            its General Partner

                                    By:     /s/  Xxxxxxxx X. Xxxxxx
                                            -----------------------------
                                            Name: Xxxxxxxx X. Xxxxxx
                                            Title:  Managing Director

                                    WPG INSTITUTIONAL SOFTWARE FUND, L.P

                                    By:     XXXXX, XXXX & XXXXX, LLC
                                            its General Partner

                                    By:     /s/  Xxxxxxxx X. Xxxxxx
                                            -----------------------------
                                            Name: Xxxxxxxx X. Xxxxxx
                                            Title:  Managing Director

                                    XXXXXXXX X. XXXXXX

                                    By:     /s/  Xxxxxxxx X. Xxxxxx
                                            -----------------------------
                                            Name:  Xxxxxxxx X. Xxxxxx