EXHIBIT 2

JOINT FILING AGREEMENT

                The undersigned hereby agree to the joint filing of the Amendment No. 7 to Schedule 13 D to which this Agreement is attached.

Dated:  June 11, 2008

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/ Mark Buckley
		Mark Buckley
		Attorney-in-Fact for Daniel J. Donoghue
		Attorney-in-Fact for Michael R. Murphy