For making groups in Entrouage use the steps below. One thing to point out is groups made in Entourage are store in the local mac address book and not on the server account.
1. Choose the Address Book icon from your icon bar.
2. Right click the Address Book button found under the On My Computer tab and select New Group.
3. A window should appear. Enter a desired group name and begin the process of entering the names/email addresses of those that you wish to be included in this group list. Save when done.
4. NOTE: Entourage groups are saved in the local Address Book of Entourage! The group is not listed in your Exchange contacts folder!
5. You should now see the newly created group in your address book.
6. Move back to your Inbox and you may begin to address email messages to your newly created group. .
Now unfortunately Entourage doesn't support syncing of Groups from Exchange to Entourage. So you wont be able to sync groups because Entourage and outlook groups are slightly different. So they are not a compatible sync and the groups need to be recreated in Entourage