If you're going ITX, your biggest problem is the GTX580 with the Accelero Xtreme - a 3-slot-solution, if I'm not mistaken.
There are not many ITX-cases that can take a 3-slot-cards. The only ones that come to my mind are the Lian Li Q11, Q18 and Q25. The Q11 cannot take a card of the length of the 580 and the Q25 is a server-solution. Which leaves the Q18 as the only viable case.
It's a beautiful case, but like all Q-cases by Lian Li it has the disadvantage of hanging the PSU above the mainboard. That limits the size of the CPU-cooler. Options:
Use a low-profile cooler like the Scythe Big Shuriken. Con: won't cool an oc'ed 2500k quietly or very well.
Use a big top-down cooler like the Thermalright AXP-140 and use the PSU-fan as the CPU-fan. This is done here: viewtopic.php?f=20&t=65338
I am sceptical of the longevity of this solution.
Use a closed-loop watercooler like Corsair H60. Con: won't be quiet at all.
Use the Silverstone SST-ST45SF-G PSU, a small form factor PSU and a big top-down-cooler like the AXP-140. Probably the best compromise, but also the most costly solution.
Other options: sell your GTX 580 on ebay, buy a 660 Ti from Asus or Gigabyte. They are 2-slot-solutions and are said to be quiet AT IDLE. Not at load though.
They will open up a bunch of other cases to choose from.