Exhibit A
AGREEMENT REGARDING THE JOINT FILING OF SCHEDULE 13D
Each of the undersigned hereby acknowledges and agrees, pursuant to the provisions of Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, that the Schedule 13D to which this Agreement is attached as an Exhibit, and any amendments thereto, will be filed with the Securities and Exchange Commission jointly on behalf of the undersigned.
Date: June 8, 2007
| MADISON DEARBORN PARTNERS, LLC | ||
| By: |
/s/ Mark B. Tresnowski | |
| Name: |
Mark B. Tresnowski | |
| Its: |
Managing Director and General Counsel | |
| VH HOLDINGS, INC. | ||
| By: |
/s/ Benjamin D. Chereskin | |
| Name: |
Benjamin D. Chereskin | |
| Its: |
President and Assistant Secretary | |
| VH MERGERSUB, INC. | ||
| By: |
/s/ Benjamin D. Chereskin | |
| Name: |
Benjamin D. Chereskin | |
| Its: |
President and Assistant Secretary | |