It sounds like your organization may not be able or willing to send you to education or get outside assistance for this project. I consider both education and outside assistance to be a must for this application as it it complex to implement. In addition, e-mail seems to have become more of a critical business service than it ever was before. But if you cannot get outside assistance or the company pay for education, then your next best option would be self-education. I would recommend that you go to the Microsoft website and go through the Virtual Labs offered for Microsoft Exchange 2007. There are over 50 separate training segments that you can find on this site. This resource will help you get up to speed on Exchange 2007. You should also buy one of the Exchange 2007 Unleashed guidebooks as that will be a great resource to have on your implementation journey.
Good luck! You will definitely need it if you are going to do this yourself and have never done an implementation from the ground up before.