VB.Net - Get Directory / Folder Size

Public Function GetFolderSize(ByVal path As String, _
                ByVal includeSubFolders As Boolean) As Long

     GetFolderSize = 0

     Dim main_dir As New System.IO.DirectoryInfo(path)
     Dim dir_files() As FileInfo

     If includeSubFolders Then
         dir_files = main_dir.GetFiles("*", SearchOption.AllDirectories)
     Else
         dir_files = main_dir.GetFiles("*", SearchOption.TopDirectoryOnly)
     End If

     For Each ofile As IO.FileInfo In dir_files
         GetFolderSize = GetFolderSize + ofile.Length
     Next

End Function