Building a new system. Need pointers

[Infrantic]

So, I am planning in building a new gaming rig.
My current rig is about 3.5 years old now, so I need an upgrade soon, so I have been looking around for new hardware.
So far my plan is to keep my HDD, PSU and drives as they are.
I'm fine without an SSD at the moment, but I might get one later on.
My PSU is a OCZ GameXStream 850Watt.


Approximate Purchase Date: Within a month or two


Budget Range: $1300-1500


System Usage from Most to Least Important: Foremost gaming.


Parts Not Required: Keyboard, Mouse, Monitor, PSU (Current OCZ GameXStream 850Watt), HDD and CD/DVD Drive



Country of Origin: Denmark


Parts Preferences: Intel CPU and ATI video card a must.


Overclocking: No


SLI or Crossfire: No


Monitor Resolution: 1920x1200


Additional Comments: I'm building a silent PC, so I'm getting the Antec P183 as well as mostly 120mm fans with the Gelid Tranquillo CPU Cooler.

The components I've been looking at are;

CPU: Intel i7-2600K 3,4GHz
GPU: ASUS Radeon HD6970 2GB
Motherboard: Asus P8P67 Deluxe
Alt. Motherboard: ASRock Z68 Extreme4 Gen 3
RAM: G.Skill Sniper Series PC3-14900 1866MHz 8GB
Case: Antec P183 V3

The one thing I'm a bit confused about, are the Motherboards, I've looked into the P67 and Z68, but I don't have the knowledge to choose wisely between the two motherboards I've been looking at.

Any info/pointers would be appreciated

 

[Infrantic]

For reference my old setup is:

CPU: Intel Core 2 Duo E6850 3.0GHz
GPU: 2xATI Radeon HD3870 512MB in Crossfire.
Motherboard: ASUS P5K Premium Black Pearl Edition
RAM: Corsair Twin2X - 4x1GB
HDD: Western Digital 500GB 7200RPM