your power suply is enough but it would be work hard every day if you choose 550 watt..
i suggest you, to pick at least 600 watt psu, to keep your system healthy. Because you plan to add some 12" fan in your case..
You can search azza solano for case via google, my be you'll be interest..
Because it has 2x20"top and side fan 2x14" front fan and 1x12" rear fan..