This is my current setup and planning for introducing excahnge 2007

I have two BES servers, both at 4.1 SP4 latest MR
DB for BES is hosted on a seperate box

Exchange 2003 SP2

I am planning to install exchange 2007 as following

1. Install & setup exchange 2007

2. Migrate users to your Exchange 2007 server

3. From the Exchange 2007 server open the “Exchange Management Shell” which can be found in the Exchange program group. From EMS run the following two scripts to set the delegate control and required permissions:

get-mailboxserver <mail_server_name> | add-exchangeadministrator BESAdmin –role ViewOnlyAdmin

get-mailboxserver <mail_server_name> | add-adpermission –user BESAdmin –accessrights ExtendedRight –extendedrights Send-As, Receive-As, ms-Exch-Store-Admin

4. Stop all the Blackberry services and remove ESM for Exchange 2003 from ONE BES server. lets call it BES02 Or unregister mapi32.dll and cdo.dll if the files had just been registered manually without installing ESM.

5. Download and install Microsoft Exchange Server MAPI Client and Collaboration Data Objects 1.2.1 BES02.

6. Restart BES server.

so all users that I migrate to Exchange 2007, move their mailboxes to BES02 server

should i move them to BES02 prior to moving them to exchange 2007 and making changes to cdo and mapi32 ? Or After mailbox move to exchange 2007 and cdo and mapi32 update on BES02 ?