Dim ordner As String = "J:\Daten"
   Dim filenames As New System.Collections.Generic.List(Of String)
   'Unterordner ermitteln 
   Dim dircol As System.Collections.ObjectModel.ReadOnlyCollection(Of String) = _
   My.Computer.FileSystem.GetDirectories(ordner)
 
   'Files im Ordner
   For Each file As String In My.Computer.FileSystem.GetFiles(ordner)
        filenames.Add(file)
   Next file
 
   'Unterordner 
   For Each direct As String In dircol
       'Files im Unterordner Direct
       For Each file As String In My.Computer.FileSystem.GetFiles(direct)
                filenames.Add(file)
       Next file
   Next direct