Just realized I forgot to answer a question you had. As far as power supply goes. I have one system with a Rosewill Bronze 80 600 watt and while the power supply works, I dont have much trust in it. It came bundled with a older gaming system that I picked up for free that the prior owner bought a power supply for it and went low cost. I heard that the prior owner was complaining that it costs $20 at his local dump to get rid of his computer, so I offered to take it away for free as for the huge gaming case alone was worth saving.
I personally dont have much faith in Rosewill products, I have run into quality issues with their products. When you plan on getting the video cards, I would also plan on getting a better power supply from Corsair, XFX, or EVGA. If the Rosewill fails due to quality issues you could smoke your entire system, thats why having a reliable and quality brand power supply I feel is the most necessary part of any computer build or power supply replacement.