Is there a reason why you should not use Entourage? Yes, there is.
Instead, the Microsoft Business Unit foisted a bloated POS on its customers that is not terribly good at anything, but is bad at a lot of things. What MacOS X users need is a port of Outlook, even if it is limited like the last version ( Outlook 2001) to accessing Exchange servers exclusively.
I have participated in quite a few of these threads but never started one. But a search of this forum will reveal that there are stretches when a new thread each day related to one or more problems with Entourage is created.