Macs come with itunes pre-installed. iTunes has an equalizer built in.
I've got itunes on my windows pc, if I go to the 'View' menu, there's a part near the bottom called 'Show Equaliser'. Admittedly, it's not fantastic, but you can manually control it if you wish.
It's definitely not going to make the speakers on a 13" laptop sound amazing, you're better off buying a quality set of headphones/speakers!