Imports System.Management
' ...
Dim Disk As New ManagementObject("Win32_LogicalDisk.DeviceID=""C:""")
Dim DiskProp As PropertyData
For Each DiskProp In Disk.Properties
if DiskProp.Name.ToUpper = "FREESPACE" Then
  Me.ListBox1.Items.Add(String.Format("{0} = {1}", DiskProp.Name, _
    DiskProp.Value))
End If
Next

        MessageBox.Show(New IO.FileInfo("C:\..File.txt").Length)