I'd build my own to be honest. There's a lot of issues in that build.
Get a 3570K. It'll perform better when gaming, use less power, and cost much less.
Sabertooths are overpriced. If you're in the US Newegg will give you 8GB RAM free with an ASRock Z77 Extreme4.
I'm not sure I would trust Digital Storm to pick a PSU. 1kW is about what you need with 2x580s and an LGA1366 chip, but overkill if you got a 7970 GHz Edition and i5-3570K. Which would probably perform better.
Get a 128GB SSD; 80GB is on the small side. OCZ Vertex 4 or Samsung 830 is my advice.
You don't need a Caviar Black for a storage drive. Anything will do.
No need for two ODDs, get a single DVD drive (cheapest possible) or Blu-Ray if you want to watch them on your PC.
Mobos come with integrated ethernet. No need to buy another.
Get a 7970 GHz Edition. Cheaper, cooler, and performs better. Few games use PhysX anyway.
Closed loop coolers are usually outperformed by cheaper air coolers eg CM Hyper 212 Evo.
The system is OK if you bought it a year and a half ago but right now it's pretty outdated.Im not saying it won't max out pretty much every game but you can get a newer ,better PC for about 1000 dolars.
If you're looking for ways to upgrade it I have to say there isn't a lot. You could replace Mobo/CPU/RAM, but you wouldn't see any more performance. New GPUs would cost tons and 580SLI is still very fast; you'd be looking at a 7970GHz edition just to get a sidegrade.
My advice would probably be a monitor or peripheral upgrade. According to ASUS you can't tri-SLI on that board.