'byte copy
My.Computer.FileSystem.WriteAllBytes("output.txt", _
  My.Computer.FileSystem.ReadAllBytes("input.txt"), False)

'text copy
Using input = IO.File.OpenText("input.txt"), _
      output As New IO.StreamWriter(IO.File.OpenWrite("output.txt"))
  output.Write(input.ReadToEnd)
End Using

'Line by line text copy
Using input = IO.File.OpenText("input.txt"), _
      output As New IO.StreamWriter(IO.File.OpenWrite("output.txt"))
  Do Until input.EndOfStream
    output.WriteLine(input.ReadLine)
  Loop
End Using