You don’t need Outlook for OWA. It is a feature of Exchange 2003. You can access it by http://SERVER_IP_ADDRESS/Exchange.
Do not install Outlook components on an Exchange server. Mshen is right, OWA is part of Exchange, installing Outlook is not required and is <a href=”http://support.microsoft.com/kb/266418″>not supported by Microsoft on an Exchange server.</a>