My question involves landlord-tenant law in the State of: California

I have a tenant who gave me her 30 days notice to vacate which means she should have been out of the house on March 31, 2008. Well, she's still in the house, and I have secured renters to move in on April 21 (Yes, this Monday). What are my rights as far as making sure she gets out of the house? Can she legally stay in the house since she gave me notice and I've already secured a new renter for the month of May?