cannot install office2003 over officeXP/w Outlook2003

I created an unattended MST file that removes officeXP and installs office2003. It works on machines that only have officeXP installed but I have machines that have Outlook upgraded to the 2003 version. The unattended setup fails to install the entire Office2003 suite on those machines with the hybrid OfficeXP/Outlook2003. Is there a command or modification on the MST file that I have to make to force a complete installation of Office2003? (If I use the custom maintenance wizard, it will add all the office2003 components but will not uninstall officeXP).