$params = array(
			'conditions'=>array('ProductCategory.parent_id'=>0),
			'order' => 'ProductCategory.name',
			'recursive' => 2,
			'contain' => array(
					'ChildProductCategory' => array(
								'conditions' => array(
										'ChildProductCategory.product_count >' => 0
								),
								'ChildProductCategory' => array(
											'conditions' => array(
													'ChildProductCategory.product_count >' => 0
											),
								),
					),
			)
		);