Hello, I am planning on transitioning our existing 2 server (1 FE, 1 BE) Exchange 03 organization to Exchange 2007 in the near future. I am a little confused by the roles and how I should best split them among servers. I only have 2 servers to work with...what roles should go together? We have a DMZ, but currently no Exchange servers reside in it. Should I plan on having one there?Thanks

Hi Travis, Its really difficult to have high availability solution with 2 servers and it requires minimum 4 servers. However for your 2 server implementation, you can place a Mailbox role on one server and CAS + Hub on another server if you are concerned about the load on your servers. If server is capable to handle load then you can put all three roles on both of the server for kind of high availability for CAS & Hub role and with SCR for mailbox server role. If you are planning to place Edge server in DMZ for internet mail flow then you don't have really option and need to put all other server roles (Mailbox+CAS+Hub)on second server. If you don't want to put Edge then Hub can also handle internet mailflow in above two situation. Check the checklist for your server roles for required memory, processor and storage. Planning Checklist http://technet.microsoft.com/en-us/library/bb125239.aspx

As Amit showed, we still can design a suitable exchange 2007 for the environment, even it just has two servers. I think that you may want to browse the articles below at first, get most important info about the planning and deployment of exchange 2007 Frequently Asked Questions Deploying Server Roles Then, when you know well about the roles and the design which you want, the article below will show you the migration procedure from exchange 2003 to exchange 2007 How to Transition from Single Forest to Single Forest