EXHIBIT 1

JOINT FILING AGREEMENT

The undersigned hereby agree to the joint filing of the Amendment No. 3 to the Schedule 13D to which this Agreement is attached.

Dated:  April 5, 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