How to remove Active Directory Connectors before installing Exchange 2007

"Microsoft® Exchange Server 2007 setup cannot continue because one or more Active Directory Connectors have been found..."

This is the error you get when Exchange 2007 setup tries to run /PrepareLegacyExchangePermissions command and founds out that you have one or more Active Directory Connectors (ADC) installed in your organization. You should remove all Active Directory Connectors from organization prior to installing Exchange 2007. I suggest that you first run Exchange Best Practices Analyzer with Exchange 2007 Prerequisites Check before you start with Exchange 2007 installation.

To remove Active Directory Connector components

1. To disable the ADC service on the server that is running the ADC service, right-click My Computer on the desktop, and then click Manage
2. Expand the Services and Applications node, and then click the Services node.
3. In the right pane, right-click Microsoft Active Directory Connector and then click Properties.
4. Change the Startup Type to Disabled. The next time that the computer starts, the ADC service will not start.
5. Click Apply, and then click OK.
6. To uninstall the ADC service, use the Active Directory Installation Wizard on the Microsoft Exchange 2000 Server or Microsoft Exchange Server 2003 CD. Open the \ADC\I386 folder and double-click the Setup.exe program. Follow the prompts to Remove All ADC service components.

Note:
You must complete step 6 and Remove All ADC components to resolve this issue. It is insufficient to disable the ADC service.

If you somehow removed the server with ADC installed from your organization without completing this steps than there is always possibility that the object still resides in Active Directory. To remove it manually follow the procedure which assumes your Exchange server was not Domain Controller:

Suggestion: Create backup of System State on at least two DC's before this procedure

1. open Active Directory Sites And Services
2. Check if there is an object of removed server under the Site where this server resided
3. Delete this object with all sub-objects
4. Replicate changes to all other DC's

Using ADSIEdit:

1. Install Support Tools from Windows 2003 CD
2. Open Microsoft Management Console (mmc)
3. Add ADSIEdit snap-in
4. Connect to Configuration Container
5. Expand Configuration --> Services --> Microsoft Exchange --> Active Directory Connections
6. Delete ADC under Active Directory Connections
7. Replicate changes to all Domain Controllers

After you complete these steps, rerun the Exchange 2007 setup or setup.com /PrepareLegacyExchangePermissions command, depends on whatever you run first.