JOINT FILING AGREEMENT

                                                                       EXHIBIT C



                             JOINT FILING AGREEMENT

         The undersigned, and each of them, do hereby agree and consent to the
filing of a single statement on behalf of all of them on Schedule 13D and
amendments thereto, in accordance with the provisions of Rule 13d-1(k)(1) of the
Securities Exchange Act of 1934, as amended.

Dated: June 12, 2002

                                       XXXXX FAMILY PROPERTIES, LTD., a
                                         Texas limited partnership

                                       By: XXXXX OPERATIONS, INC., its
                                         General Partner

                                       By:   /s/  J. Xxxx Xxxxx
                                             -----------------------------------
                                             Name:    J. Xxxx Xxxxx
                                             Title:   President


                                       XXXXX OPERATIONS, INC.

                                       By:   /s/  J. Xxxx Xxxxx
                                             -----------------------------------
                                             Name:    J. Xxxx Xxxxx
                                             Title:   President


                                         /s/ Xxxxxxxx X. Xxxxxxx
                                         ---------------------------------------
                                             Xxxxxxxx X. Xxxxxxx


                                         /s/ Xxxx Xxxxxxxx Xxxxx Xxxxx
                                         ---------------------------------------
                                             Xxxx Xxxxxxxx Xxxxx Xxxxx


                                         /s/ Xxxxxx Xxxxxxxxx Xxxxxxxxx
                                         ---------------------------------------
                                             Xxxxxx Xxxxxxxxx Xxxxxxxxx


                                       ESTATE OF XXX X. XXXXX

                                       By:   /s/  J. Xxxx Xxxxx
                                             -----------------------------------
                                             J. Xxxx Xxxxx, Independent Executor