Welcome back to the forum!
How much do you have to play with your budget? What games do you play? Are you going to be using this PC for other tasks/apps? What exactly are you coming off of (list your current PC specs), mainly what case you would be sticking the new stuff in?
And just to note, if you can't wait for Ivy Bridge, 7800 series AMD gpu's or nvidia kepler cards, then building your new rig around the i5 2500k is still a very good choice. As for the 580 gtx... not so much. AMD's new 7970 beats it by 30%+ for the same price and honestly, EVGA has some killer sales on newegg right now for the older GTX 480 for $250 a piece. They perform the same as the GTX 570's but they do take more power; for the price point, its a sick price (specially if you are like me and need a few gpu's to warm up your room... lol).
The best in value z68 motherboard to pair with current gen sandy bridge chips (and future ivy bridge) is the Asrock Extreme3 Gen3 motherboard. For $130, you get a lot of features with quality components without all the extra stuff you don't need or the high price tag. It still supports both a two card SLI/xfire setup and the new pcie 3.0 interface (but you need a 3.0 capable GPU and CPU (ivy bridge) to take advantage of this). It's also stable at high overclocks of 5ghz, provided you have proper cooling.
And holy crap on the ram dude... you will be paying almost double the price from going 4GB to 8GB sticks, specially considering for a gaming rig, you won't really need anything more than a simple $40-50 set of 8GB (2x4gb) or grab a 16gb kit (4x4gb) for half the price of the one you selected. I doubt you would ever use that much anyhow, or need all 32GB of space on this type of rig.
As for Power Supply, for that price, I'd look at other offerings. You would be paying quite the premium for 80+gold standard efficiency below 850w. For not a whole lot more, you can get the OCZ ZX or Z series PSU that are 80+gold rated for cheaper or similar price point. I run the 850 that I got for $80 AR and supports my triple 570 SLI setup. The 1000w versions were $110 during the same sale and kinda wished I bumped it up to that so I had some OC headroom. For a two card solution, 850 would be enough with OC. If you went with the 480 deal, I'd say bump it up to the 1000w, they eat a lot more power each (Over 300w each compared to 220-250w of the 580 at stock).
Here's what I listed: