URL := 'http://www.whois.net/whois_new.cgi?d='+Form1.StringGrid1.Cells[1, Form1.StringGrid1.Row];

unit TBackgroundDownloaderUnit;

interface

uses Classes, Windows,
  IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, IdHTTP;

type
  TReplyReceivedEvent  = procedure (URL, Reply: string) of object;

  TBackgroundDownloader = class (TThread)
                            URL, Reply     : string;
                            OnReplyReceived : TReplyReceivedEvent;
                            IdHTTP         : TIdHTTP;

                            constructor Create (CreateSuspended: boolean);

                            procedure CallUserEvent;
                            procedure Execute; override;
                          end;


implementation

constructor TBackgroundDownloader.Create(CreateSuspended: boolean);
begin
  inherited;
  IdHTTP := TIdHTTP.Create(nil);
end;

procedure TBackgroundDownloader.CallUserEvent;
begin
  if Assigned(OnReplyReceived) then
    OnReplyReceived (URL,Reply);
end;

procedure TBackgroundDownloader.Execute;
begin
  Reply := IdHTTP.Get (URL);

  Synchronize (CallUserEvent);

  IdHTTP.Free;
  IdHTTP := nil;
end;

end.

 
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private-Deklarationen } 
  public
    { Public-Deklarationen } 
    procedure IrgendeinName(URL,Reply: string);
  end;

var
  Form1: TForm1;

implementation
uses TBackgroundDownloaderUnit;

{$R *.DFM} 

procedure TForm1.IrgendeinName(URL,Reply: string);
begin
  MessageDlg ('Von der URL'#13#10+URL+#13#10+'kam folgendes zurück:'#13#10#13#10+Reply, mtInformation, [mbOk], 0);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  with TBackgroundDownloader.Create (true) do
  begin
    URL := 'http://www.quellcodes.de/';
    OnReplyReceived := IrgendeinName;
    Resume;
  end;
end;

end.