How can you easily check the http error number of a webclient?

[alex21]

I'm trying to detect the http status number such as (401 Unauthorized) from a 'WebException' when a WebClient in my code fails.

Public Function DataSources_ValidURL() As Boolean
        Dim TestClient As New WebClient()
        TestClient.BaseAddress = DataSources_FilePath
        Try
            TestClient.DownloadString(DataSources_FilePath)
        Catch ex As WebException
            If ex.Status = 401 Then
                MessageBox.Show("Testing")
            End If
            If ex.Response.Headers.AllKeys.Contains("WWW-Authenticate") Then
                If MessageBox.Show("The remote server is requesting a username and password.", "Password Required", MessageBoxButtons.YesNo) = Windows.Forms.DialogResult.Yes Then

                Else

                End If
            End If

            MessageBox.Show(String.Format("An error was encountered whilst trying to connect to the entered web address: {0}", ex.Message), "Error Encountered")
            Return False
        End Try

        Return True
    End Function

I would rather check for the error number then for an authentication header...

 If ex.Response.Headers.AllKeys.Contains("WWW-Authenticate") Then

Does anyone know how to simply check for a 401 status return from a WebException.

Thanks