Code:

uses

registry;

function IE_installed(var Version: string): Boolean;

var

Reg: TRegistry;

begin

Reg := TRegistry.Create;

with Reg do

begin

   RootKey := HKEY_LOCAL_MACHINE;

   OpenKey('Software\Microsoft\Internet Explorer', False);

   if ValueExists('Version') then

     Version := ReadString('Version')

   else

     Version := '';

   CloseKey;

   Free;

end;

Result := Version <> '';

end;

procedure TForm1.Button1Click(Sender: TObject);

var

IE_Version: string;

begin

if IE_Installed(IE_Version) then

   ShowMessage(Format('Internet Explorer %s installed.', [IE_Version]));

end;