Microsoft Exchange Server 2007

I’ve been doing some reading on Exchange Server 2007 trying to get ready for implementing it into our organization. We have 8 sites, but only about 175 mailboxes total. In my reading, it sounds like Microsoft says I should have a hub transport and mailbox server at each site. For the small amount of mailboxes and users, I should be able to get by with one server covering the whole company.

What type of things have you encountered as you have implemented 2007 into your organizations? It can be related to my situation or otherwise. I would just like to see what others are experiencing.