Question : Exchange 2007 Changing GC server

I am currently Running Exchange 2007 on a Windows Server 2003 R2. I have 2 Windows Server 2003 Domain Controllers. I need to take one of the DC's offline for updates and maitnance. This DC happens to be the GC server. I found out the hardway that if this Server goes offline Exchange stops working. Then i tried to move all the roles over to the second DC and turned the GC off on the first DC Exchange stopped working again.

These are the steps i took when i tried to change all the roles over.
- Change the RID, PDC, and Infrastructure through users and computers
- Change the GC role through sites and services
- Changed the naming master through domains and trusts

Basically i need help with how to do this.
Am I missing a step?
Is there something i have to do on the Exchange server?

Answer : Exchange 2007 Changing GC server

when you have taken the main GC offline and made the 2nd DC a GC server and take on all the FSMO roles all you will need to do on the exchange server is just to simply restart it. This binds the exchange server to the new GC server.

also why dont you just make both the servers GC servers any way? its best to have this for backup