EXHIBIT 1

JOINT FILING AGREEMENT

The undersigned hereby agree to the joint filing of the Amendment No. 2 to the Schedule 13D to which this Agreement is attached.

Dated:  March 30, 2007

DISCOVERY GROUP I, LLC,
for itself and as general partner of
DISCOVERY EQUITY PARTNERS, L.P.

 

 

 

 

 

 

 

By

Michael R. Murphy*

 

 

Michael R. Murphy

 

 

Managing Member

 

 

 

 

Daniel J. Donoghue*

 

Daniel J. Donoghue

 

 

 

 

Michael R. Murphy*

 

Michael R. Murphy

 

 

 

 

 

 

 

*By:

/s/ Robert M. McLennan

 

 

Robert M. McLennan

 

 

Attorney-in-Fact for Daniel J. Donoghue

 

 

Attorney-in-Fact for Michael R. Murphy