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Launch Entourage. Click the "File" menu and select "Export."
Select the "Items to an Entourage Archive" radio button. Tick the check boxes for each type of content you want to export.
Click the "Right Arrow" button to continue, and then select "Yes, Delete Items From Entourage After They Are Archived." Click the "Right Arrow" button.
Click "Save" to save the archive to your desktop and then click "Next."
Transfer the archive to your new iMac.
Open Entourage on the new iMac.
Click File and select Import, then choose the archive you created.
Follow the steps to complete the import process.
Sorry, my previous reply appears not to have gone through.
Did the directions work for you?