If this PST file was created in Outlook 2003, it will not be compatible with
earlier versions (i.e., won't cause any damage, but won't be able to be
opened or imported). To transfer data from Outlook 2003 to earlier versions
you would first have to create an "Outlook 97-2002" PST file (New > Outlook
Data file...) in Outlook 2003 and copy the data into it.