These are the steps you should follow in order to connect MacOSX to an existing active directory domain. I tried this using MacOSX Snow Leopard 10.6.2. The domain server is Windows Server 2003.
- In the Mac, go to System Preferences -> Accounts
- Click the lock icon to unlock it and enter the admin password to gain access to administrative settings.
- Click "Login Options"
- Under "Network Account Server", click "Join"
- In the popup, click "Open Directory Utility" and make sure all the tick marks are checked.
- In the "Server" field, enter the server name (without "\\" or anything) which is hosting the active directory service.
- If it finds the server, it will ask you for the information shown below:
- Make sure to use the client computer ID that your administrator has given.
- Enter the correct details for the settings and click OK.
To login as a domain user, enter the user name in the usual domain\username format in the MacOSX login window.