Exhibit B JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13G, and any further amendments thereto executed by each and any of us shall be filed on behalf of each of us pursuant to and in accordance with the...

Exhibit B

                             JOINT FILING AGREEMENT

         The  undersigned  hereby agree that the  Statement on Schedule 13G, and
any further  amendments thereto executed by each and any of us shall be filed on
behalf of each of us pursuant to and in accordance  with the  provisions of Rule
13d-1(k)(1) under the Securities Exchange Act of 1934, as amended.

         This Agreement may be executed in separate counterparts,  each of which
shall be deemed an original,  but all of which shall constitute one and the same
instrument.

Dated: September 7, 2007

                                                POTOMAC CAPITAL MANAGEMENT LLC

                                                By: /s/ Xxxx X. Xxxxx
                                                Xxxx X. Xxxxx, Managing Member


                                                POTOMAC CAPITAL MANAGEMENT INC.

                                                By: /s/ Xxxx X. Xxxxx
                                                Xxxx X. Xxxxx, President

                                                XXXX X. XXXXX

                                                By:   /s/ Xxxx X. Xxxxx
                                                Xxxx X. Xxxxx