|File, Import and Export, Export to pst file, select Calendar, Next, browse to the path where your current pst file is, and assign a filename, Ok, Finish, OK.|
The next steps will depend on what version of Outlook you have. These instructions are for 2003.
Close Outlook, Control panel, Mail, Data Folders, Add, Select the top option, OK, browse to the same path and select the newly created file, OK, OK, Close.
E-mail Accounts, View or change existing accounts, Deliver new email to the following location: click on the drop down and select the bottom Personal Folders, Finish Close.
Reopen Outlook. You will get a message that the location for your email has changed. Click OK and Outlook will close. Reopen it. New mail will be delivered to the newly created file, and you'll have your copied Calendar entries. You'll also see the old Personal Folder in the list.
I would recommend at some point, going back into the Data Files options, click on the original file, settings, and compact.
That's it. Pretty straight-forward.