Since you can install only one version of Outlook at a time, either Outlook
2003 with BCM or Outlook 2007 with BCM, you have to uninstall Outlook 2007,
then reinstall Outlook 2003, then reinstall BCM 2003. And that's not always
trouble-free.
And to "guzzi", search this group for "2007 install" and you should find a
few posts about how to resolve install issues.