I read Crawford's enlightening journal article in the Spring 2011 Intercollegiate Review and am delighted to see it is available online. The four myths he cites are the following:
Myth #1: The crusades represented an unprovoked attack by Western Christians on the Muslim world.
Myth #2: Western Christians went on crusade because their greed led them to plunder Muslims in order to get rich.
Myth #3: Crusaders were a cynical lot who did not really believe their own religious propaganda; rather, they had ulterior, materialistic motives.
Myth #4: The crusades taught Muslims to hate and attack Christians.
This is a truly excellent piece of work. Highly recommended. Read it in its entirety here.