Imports System.Threading
Imports System.IO

Private T As Thread
Private OrgF As String
Private NewF As String
 
Private Sub Button1_Click(ByVal Sender As Object, ByVal e As EventArgs)
  T = New Thread(AddressOf CopyFile)
  OrgF = "C:\Datei.dat"
  NewF = "C:\Neue Datei.dat"
 
  T.Start()
End Sub
 
Sub CopyFile()
  Dim OrgFile As New FileStream(OrgF, FileMode.Open)
  Dim NewFile As New FileStream(NewF, FileMode.Create)
 
  Dim BR As New BinaryReader(OrgFile)
  Dim BW As New BinaryWriter(NewFile)
 
  Do Until BR.PeekChar = -1
    BW.Write(BR.ReadBytes(1073741824)) '1 MB
    Progressbar1.Value = CInt(NewFile.Length * 100 / OrgFile.Length)
  Loop
End Sub