Sometimes you cannot reinstall an application because the installer
package looks in the registry for existent keys,belonging to the application
you want to install.(it checks if the application is/was already installed)
After a canceled Office 2003 Installation there are left behind traces in the
registry,which can prevent a proper reinstall,because the installer
package recognizes the application as installed already.You can remove
these left behind keys manually by navigating to:

- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Delivery
\SourceEngine\Downloads\microsoft.watson.alrtintl.data\

Select the microsoft.watson.alrtintl.data key and delete it.

Now navigate to:

- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Delivery
\SourceEngine\Downloads\microsoft.watson.watsonrc.data\

Select the microsoft.watson.watsonrc.data key and delete it.

Note:In an enterprise environment the installer packages may differ from
each other and a succesfull install depends on the in the installer package
set parameters.It is possible that in some environments an installation
is succesful after a canceled install without removing this keys !!