I recently set up a new Mac Pro. I installed Office 2004 and copied the user's files over. Entourage started fine, and the user's Exchange mailbox seemed to open correctly.
I patched the installation of office, and Entourage started crashing shortly after launching it. I then removed Office 2004, and reinstalled it. This time, Entourage said that it could not open this version of the database. I patched 10.5.2 to 10.5.8, to no avail.
I tried various fixes other people suggested on the web. In the end, I patched 2004 with the latest patch, killed the Microsoft Database process. Since the user did not keep a PST, I simply moved the user's Entourage data in documents (In a Microsoft folder) to another location - and then reconfigured the entourage client for exchange.
Entourage opened with no issues.