You don't have anything in there that uses a lot of power. Even in full draw I doubt such a system will use more then 150W. (unless I missed the GPU) Any quality 350-450W PSU will do fine. I'd be careful going higher then 450W as it will start to be horribly inefficient as you go higher. If a PSU is most efficient at its 50% mark then that means you need a 300W PSU. The corsair mentioned earlier is a good choice, as is the Antec 380W Green.