I don't trust the Kingwin brand either. But not from bad experience, just never dealt with one.
Thing is, I'm only using a 520w Dynex psu. So, I definitely need some upgrade. Even if it just a 750w, or even 650w. Something with good quality.
I could get a get a Galaxy GTX 670 for $250. No power supply though. I can probably talk the kid down to $225, but if not, he wants $250. Would I be better off going for that?