Outlook 2000:
Display the calendar then ... View, Current View, Define views select a table view, copy it. Customise it - in particular removing any filters. then apply it. Click on Calendar in the folder list. Edit select all. right click on the calendar items and choose delete.
In Outlook 2000 there is a 'changed by' field for example that might help in distinguishing the users appointments from the imported ones - filter them out. That said it appearsto be blank in my set up.
Alternatively within this view it is quite easy for the user to scroll down the list deleting as required.
Thanks,
Gavin