Go with the i5-2500k, there is no difference in gaming when comparing the i7-2600k against the i5-2500k, it'll also save you 100$ to put toward something else!

Ditch the Antec 900, it is way outdated and has since been revised. If you like the styling, get an Antec 902 Rev. 3 or a 1200. Whatever case you do get, make sure your 580 will fit.

Instead of 8 GB of slow RAM, get 4 GB of faster RAM like this:
[ Register or Signin to view external links. ]
The HyperX Blus come at a decent speed, but with some tweaking can pull 1600 mHz CL7 (Lower Cas Latency is better). Plus it is cheap. If you do need 8 GB for some reason, just get 2 sets. If you don;t like the looks, you might want to wait for these to restock:
[ Register or Signin to view external links. ]

Like Generation said, the 2500K is as good as the 2600K in games because they do not utilize the extra threads. In fact, most games don't even use more than one.

Get the Samsung Spinpoint F3 instead of the Caviar Black. They are honestly the best 1 TB drive on the market. Cheap, great track record, and very fast.

You may want to consider an SSD for a high-end build like this. It won;t help much in games, but you will see the difference in day-to-day use. Boot times will drop significantly and apps will load much faster among other things. If you don't want to get an SSD, you can also buy more than one 1 TB drive and configure them in RAID 0 (Look it up on Wikipedia if you are unfamiliar with RAID) and get a huge speed boost for not much money.

Unless you want to buy another 580 in the future, that PSU is overkill. The TDP of the 580 is 244 watts and the 2500K is 95 watts, so you would have no trouble running your system on a 650 watt. A 750 watt or 850 would be okay to handle 580s in SLI. i suggest a nice Seasonic unit with 80+ Gold certification:
[ Register or Signin to view external links. ]

With a build like this, you might want to go all out and get a Noctua NH-D14 over the Hyper 212+ if you plan on doing any serious and consistent overclocking. That's just me though. Heat scares me.

i think there are some ok specs in there, i would do what i did and instead of buying an intel core-i7 quad core, spend only $200 and buy an AMD Phenom x6 Hex core processor like i did. of course you are going to need a mobo to match the socket, but whatever. i used a gigabyte mobo with PNY 8GB ram (2 x 4 GB)

this is the processor i got..

[ Register or Signin to view external links. ]

and to be perfectly honest with you, i would strongly suggest getting a full size tower. You never know if your going to want to make additions to the rig, and you never know what your gonna want to do with cable management.

the biggest thing you want to ask yourself is..

1. is everything going to work in sync? am i gonna get ram that works with my mobo, and same goes for my processor
2. are you gonna overclock
3. are you gonna build a hackintosh

Thanks, to all three of you guys. And to r00t_b33r I think I'm going to get the Noctua like you said, but it also says its 140mm and not 120. Am I going to run into any problems with it later considering its size? (Not really that much but it can make a difference.)

I have never heard of a decent case that the NH-D14 has not fit in. Some are indeed tight, but they fit. I know for sure that it fits in the 902, too. You just have to make sure your RAM heatsinks are not too tall. The ones I posted earlier are both fine.

Do not get an AMD hexacore and think it will be better than a 2500K. More cores does not mean more performance. There are almost no applications out there that take advantage of that many cores and games use very few threads. In benchmarks, the 2500K annihilates the 1100T, even in heavily-threaded applications. There is no reason whatsoever to buy hexacores for gaming machines. Period. If you need a cheaper CPU. get an AMD Phenom II X4 955 or an X2 555 (it unlocks to a quad-core).

1. The RAM I suggested is compatible.
2. Overclocking is almost too easy on 1155.
3. Hackintoshing is actually easier on 1155 since the latest overpriced iMacs use it. If you wanted almost perfect compatibility, get a 6950 or two.

Ok cool just making sure. And I like Intel better anyway, idk why I just do haha.

And thanks for your help, helped me make some decisions that are better for the long-run.