vb Code:
  1. Public Class Form1

  2.  
  3.     Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

  4.         Using fbd As New FolderBrowserDialog

  5.             If fbd.ShowDialog = Windows.Forms.DialogResult.OK Then

  6.                 For Each foundFile As String In IO.Directory.GetFiles(fbd.SelectedPath, "*.wav", IO.SearchOption.AllDirectories)

  7.                     If ListBox1.FindStringExact(foundFile) > -1 Then

  8.                         ListBox2.Items.Add(foundFile)

  9.                     Else

  10.                         ListBox3.Items.Add(foundFile)

  11.                     End If

  12.                 Next

  13.             End If

  14.         End Using

  15.  
  16.     End Sub

  17. End Class