Workaround - run a workflow when an Appointment is created or assigned to change the organiser to match the owner (assuming you are using the owner field to show which sales person is going on the appointment).
If you do need to track the organiser as well (to measure KPIs of how many appts they make) then create a new lookup field (ie a N:1 relationship to System User) called "arranger" or something else. As this is not a special built-in field, Outlook will do
nothing with this. Again, you could use workflow to fill this in (maybe based on "created by").
Hope this helps. Adam Vero, MCT