Entourage contact and calendar syncing requires Microsoft Office 2004 for Mac Update 11.3.5 or later. If you are using Mac OS X v10.6 or later, you should use Entourage 2008 and install Microsoft Office Update 12.1.2 or later. The latest updates for Microsoft Office for Mac are accessible here, or you can use the Microsoft AutoUpdate application.
After you have installed the latest update, the Sync Services option in Entourage will be available (in Entourage, choose Entourage > Preferences and click Sync Services under General Preferences).
Choose "Synchronize contacts with Address Book and MobileMe" and "Synchronize events and tasks with iCal and MobileMe" to make Entourage contacts and calendars sync with Address Book and iCal. Then, click OK.
After you click OK in Entourage Preferences, you'll see the following dialog:
Select the sync option that represents how you want to synchronize the information you selected. If all of your information is in Entourage and not Address Book, then select "Replace Sync Services items with Entourage items." If all of your information is in Address Book, then select "Replace Entourage items with Sync Services items." If you have a mix of information in Entourage and Address Book, then you may want to select the "Merge Entourage items with Sync Services items."
Note: Entourage does not need to be open when syncing iPhone, iPad, or iPod touch. Entourage 2004 is not a Universal application and requires Rosetta when used on an Intel-based Mac. Entourage 2008 is a Universal application. Universal applications may run more efficiently on an Intel-based Mac.