1   
2   uses 
3   registry;
4   
5   function IE_installed(var Version: string): Boolean;
6   var
7     Reg: TRegistry;
8   begin
9     Reg := TRegistry.Create;
10    with Reg do
11    begin
12      RootKey := HKEY_LOCAL_MACHINE;
13      OpenKey('Software\Microsoft\Internet Explorer', False);
14      if ValueExists('Version') then
15        Version := ReadString('Version')
16      else
17        Version := '';
18      CloseKey;
19      Free;
20    end;
21    Result := Version <> '';
22  end;
23  
24  procedure TForm1.Button1Click(Sender: TObject);
25  var
26    IE_Version: string;
27  begin
28    if IE_Installed(IE_Version) then
29      ShowMessage(Format('Internet Explorer %s installed.', [IE_Version]));
30  end;