Even in a Windows 2003 AD environment Wins maybe still required, dependant on what applications you are running . However there are certain rules that must be adherred to for a healthy Wins Environment

  1.  Wins Servers should always be configured to point to themselves. This is because of the potential for split registrations. See Kb article Setting Primary and secondary WINS server options
    http://support.microsoft.com/kb/150737/

If you have a Wins Server installed on a domain controller ensure you uninstall it even if it is no long required. The reason for this is that the server will still register it has the Wins Service installed and registers its services in its own local database regardless of thwther it points to itself or not. If you do not do this you can get some unexpected error conditions and potentially Browser elections if the Wins Server was a PDCe filling your event logs.