Recently transitioned from Exchange 2003 to Exchange 2007. I am utilizing BES 4.1.3 on a separate server.

I followed the work provided by Ashworth (thanks Ashworth!) to introduce BES 4.1.3 into the Exchange 2007 environment. Less than 2 hours later my Exchange 2007 and BES were working perfectly (minus 15 minutes for a reading error and downloading the wrong Exchange CDO file).

Listed are the exact steps I used to introduce my BES in the Exchange 2007 environment:
1) Verify that Exchange 2007 is operational in your environment without errors. Send internal and internet e-mails for verify e-mail flow

2) On the Exchange 2007 server, perform the "Exchange Management Shell" steps. I was using the Windows Powershell for about 15 minutes until I realized my mistake!
a) "add-exchangeadministrator BESAdmin -role ViewOnlyAdmin" (without the quotes)
b) "Get-mailboxserver <your server name> | add-adpermission –user BESAdmin -accessrights GenericRead, GenericWrite -extendedrights Send-As, Receive-As, ms-Exch-Store-Admin" (without the quotes)
c) I had to manually add the BESadmin service account to the Organization Container on the Exchange Administrators tab granting "Exchange View-Only Administrator"
d) Wait for about 15 minutes for the changes to take effect

3) On the BES server, Uninstall the Exchange 2003 System Manager and reboot the BES server

4) On the BES server, Download and install the Microsoft "Exchange" MAPI CDO (ExchangeMAPICDO.exe) from Microsoft. Don't use ExchangeCDO.exe which doesn't supply the required MAPI support.

5) On the BES server, Verify that MAPI is working correctly. Use the BES "Edit MAPI Profile" and verify that the name is resolving correctly. Do this by re-entering the service account name and click "Check name"

6) Reboot the BES server and note the time (example, 10:43)

7) Wait for the BES server to settle and then send a couple of test e-mails from an Outlook client to a handheld user. Check the handheld for the e-mail

8) Send from the handheld to an Outlook user

9) Open the BLACKBERRY_MAGT_01_<Date>_0001.txt log and scroll down to the time the BES server was restarted (10:43). Look for errors such as "MAPIMailbox::CreateSearchFolder - Open Entry (0x80070005) failed)". Steps 2c-2d above resolved this error for me

10) If you use Symantec Backup Exec 11d for data protection. Download BE11d version 7170 from Symantec (you will need a agreement serial number) which will backup the Exchange 2007 mailboxes. You will need to install the ExchangeMAPICDO.exe on the Exchange 2007 server as well. The MAPI install allows for mailbox backup versus information store backup's

I did not have to anything on the BES other than unstall the Exchange 2003 System Manager, reboot, install the Exchange MAPI CDO, and verified the MAPI client was working.

Thanks again to Ashworth and others for their great work!