Yep. Silverstone makes great PSU's. At that capacity pushing 100A on a single rail you're definitely good there.
Well the baddest card on the planet is the AMD Radeon 6990 HD if you can find one, but it's likely to be a little out of your price range right now since volumes are so low.
In the most recent shootout from MPC the 590 won nearly every category. Not trying to argue at all, but saying it's the badest card on the planet is highly debatable. I also don't see the 6990 getting anywhere near a $500 price point for several months still at least...same with the 590.
I was looking at the 6870x2 but the price point is retarded. Nearly $500 for the x2 when you can go 6870 xfire for around $350. Dumb. So I'm looking at:
EVGA GTX 580 - $370 (B Stock) none in stock currently
EVGA GTX 570 - $250 (B Stock) none in stock currently
EVGA 460 2win - $380 - beats the 580 in nearly all benchmarks
6870 Crossfire - $360ish - (soundly beats both the single 580 and 460 2win)
6950 Crissfire - $480 (not sure it's worth it)
The price is nearly the same for the 6970 and 580 (B stock) so with the price being equal, I don't think anyone can seriously argue the 6970 is bet. That is why I have the 580 and 570 as consideration in single card format (for future SLI).