Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles MyBase.Load
        Dim rootDir As String = "x:\users"
        Dim directories As New DirectoryInfo(rootDir)
        Dim directoriesArray As DirectoryInfo()
        Dim childFile As FileInfo
        Dim childSize As Long
 
        directoriesArray = directories.GetDirectories()
 
 
        For Each direc In directoriesArray
            MsgBox(direc.Name)
            MsgBox(GetDirectorySize(direc.FullName) / 1048576)
            childSize = 0
        Next
    End Sub
 
    ' Returns the sum of the files in the folder.
    ' dPath: Path of the directory
    ' include subfolders: set if include subfolders ;)
    Public abort As Boolean
    Friend Function GetDirectorySize(ByVal DirPath As String) As Long
        Dim DirSize As Long
        Dim Dir As DirectoryInfo = New DirectoryInfo(DirPath)
 
        Try
            Dim ChildFile As FileInfo
            For Each ChildFile In Dir.GetFiles()
                DirSize += ChildFile.Length
            Next
 
            Dim SubDir As DirectoryInfo
            For Each SubDir In Dir.GetDirectories()
                DirSize += GetDirectorySize(SubDir.FullName)
            Next
 
        Catch except As Exception
            MsgBox(except.Message, MsgBoxStyle.Exclamation, "Fehler")
            Exit Function
        End Try
 
        Return DirSize
    End Function