A good quality ~500w power supply will run that system fine. Corsair, Seasonic, PC Power and Cooling, Antec, XFX, Enermax and Silverstone are all top quality brands. If you plan on future upgrades go with a 550w unit as that will run almost any single graphics card system.
I like the Samsung Spinpoint F3 for a new hard drive. It is the best "bang for your buck" drive. Fast, quiet and reliable.