Got the answer. It was right under my nose :?

Code:
procedure TForm1.Button1Click(Sender: TObject);
var
   DeviceMode:  TDeviceMode;result:integer;
begin
   EnumDisplaySettings(nil,  Cardinal(-1),  DeviceMode);
   result:=DeviceMode.dmDisplayFrequency;
   showmessage(inttostr(result)+'hz');
end;
In case you ever need it....