For a harddrive I'd suggest the Samsung Spinpoint F3 or Seagate Barracuda 7200.12 - 500GB or 1TB versions.
If you only want to power one video card than a good 550W PSU is right. If you want to crossfire then a good 750W one. So, do you want to be able to crossfire? Also do you want to have a modular one? I will come up with a suggestion once you answer these two questions. I shall point out that with a massive bottom mounted case like the HAF 922 the need for a modular PSU isn't very high, as cables can just lie on the bottom without getting in the way of airflow.