I'm not firm on the modular power supply, the one you linked looks pretty good.
I'm most curious about the GPU I've picked out. I've heard a lot of argument over the GTX 570 vs. 7850... which one is the best bang for the buck? I tend to gravitate towards Nvidia these days, hence my initial choice to go with the GTX 570.
Corsair TX series are very good power supplies, they're actually made by Seasonic.
My opinion is that between the 7850 and the GTX 570, the 7850 is the better buy. Stock to stock the 7850 is almost as good as the 570, and the 7850s are monsters for overclocking, its not unheard of to be able to overclock them 40% over their stock settings.
As far as the GTX 670, they would be better, however good luck finding them. I'm not a 100 percent sure what the problem is, but Nvidia is really getting its ass kicked right now, not because their video cards have lost a step in their performance, but they seem to be having trouble supplying enough cards to meet the demand. GTX 680s remain sold out almost everywhere, and I'm not sure the 670 is going to be in any better of a position.