Have you followed the steps in method 2 from below MS KB article?
Exchange ActiveSync and Outlook Mobile Access errors occur when SSL or forms-based authentication is required for Exchange Server 2003
If yes you will run into synchronization problems when using DirectPush. A HotFix have now been made available, for more info see below MS KB article:
Direct Push does not work in Exchange Server 2003 SP2 after you create a secondary virtual directory