Public Class Form1
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        TextBox1.Text = ""
        Dim wc As New Download.MyWebClient
        AddHandler wc.DownloadCompleted, AddressOf Download_Completed
        wc.DownloadAsync("http://www.vbarchiv.net")
    End Sub
 
    Private Sub Download_Completed(ByVal source As String)
        TextBox1.Text = source
    End Sub
End Class

Imports System.Net
 
    Public Class MyWebClient
 
        Public Event DownloadCompleted(ByVal source As String)
        Private Delegate Sub AsyncCompletedDelegate(ByVal stream As IO.Stream)
        Private mDelegate As New AsyncCompletedDelegate(AddressOf SyncCompleted)
 
        Public Sub DownloadAsync(ByVal url As String)
            Dim request As HttpWebRequest = CType(HttpWebRequest.Create(url), _
              HttpWebRequest)
            request.Method = "GET"
            Dim result As IAsyncResult = request.BeginGetResponse(New _
              AsyncCallback(AddressOf RequestComplete), request)
        End Sub
 
        Private Sub RequestComplete(ByVal result As IAsyncResult)
            Dim request As HttpWebRequest = CType(result.AsyncState, _
              HttpWebRequest)
            Dim resp As HttpWebResponse = CType(request.EndGetResponse(result), _
            HttpWebResponse)
            mDelegate.Invoke(resp.GetResponseStream)
        End Sub
 
        Private Sub SyncCompleted(ByVal result As IO.Stream)
            Using stream As System.IO.Stream = result
                Using sr As New System.IO.StreamReader(stream)
                    RaiseEvent DownloadCompleted(sr.ReadToEnd)
                End Using
            End Using
        End Sub
 
    End Class