Outlook only comes with certain versions of Microsoft Office.  As Office 2003 (what you would need to get Outlook 2003) is obsolete and has been replaced by Office 2007 (which is soon to be replaced by Office 2010) I doubt that you will be able to buy a legitimate/legal copy of Office 2003.  
Can I buy an upgrade for my Latitude D830 from Outlook 2002 to Outlook 2003? Max
upgrade from Outlook 2002 to 2003 n Latitude D830