Recently, my company implemented a new Exchange 2007 server for our email. No special changes or accommodations were made to support OS X. After a bit of searching and trial and error, I figured out the settings for Entourage to work when connected to the corporate network: email, contacts, and calendar all work.
I started with version 11.3.6 (070618) of Entourage, and added a new Exchange email account. I then tried the automatic setup, but it failed so I went into manual mode. During the setup, i found two fields that require surprising entries:
Under the Account Settings tab, the Exchange Server field. Here is what works for me:
https://my.internal.owa.server.name/exchange/username@domain.com
Be sure to use /exchange/ rather than some other directory, and include your full email address afterwards. This was surprising because to connect with Safari, the URI is:
https://my.internal.owa.server.name/owa/
On the Advanced tab, for the Public folders server, I use this URI:
https://my.internal.owa.server.name/public/username@domain.com
Once again, use /public/ not some other directory.
Evidently /exchange/and /public/ are virtual folders that Exchange 2007 creates for backward compatibility. The data for the rest of the fields was as expected.