Finalizing My Build

[BenIsLegend]

I've been struggling along with a dual core laptop with a bad graphics card that overheats at the slightest thing. I enjoy pc gaming but I haven't been able to enjoy it fully as my laptop starts to lag as soon as it gets hot. So I decided to build a new pc for myself.
I have most of the rig sorted apart from two final components. I'm on holiday atm and have two weeks left. When I get back, I'll be buying the parts so hopefully I can get this sorted within these final two weeks.

To help you guys help me, I'll tell you a bit about what I will be using the computer for.
To help with the CPU: I do render HD videos, they are on average about 10mins long. My current laptop takes 4hours to render a 10min video, any improvement on this would be great.
To help with the GPU: I am one of those people that want to play everything on max. Which unfortunately I cannot do atm, my laptop has a ATI Mobility Radeon HD 4570 which overheats a lot and when it does it makes the laptop very slow and if I'm playing a game the frame rate will drop drastically which makes the game unable. The games I would like to play on max are the obvious really:
Battlefield 3 (I'm guessing a lot of you are probably sick of people asking about system specs for this game and I do understand that no official system requirements have been announced but I know that most people reckon it will play on certain cards)
Elder Scrolls V: Skyrim
Dead Island
It will also be important to note that I will be playing at a resolution of 1920x1080.

Confirmed Components:
For i7 build: Asus P8Z68-V LE Intel Z68 S1155 Motherboard
For i5 build: Asus P8P67 Rev3 Intel P67 Express Socket 1155 Motherboard
RAM: Corsair Memory XMS3 8GB DDR3 1600 MHz CAS 9 Dual Channel Desktop
Case: Coolermaster Elite 430 Black Mid Tower Computer Case
PSU: 750W Coolermaster RS750-ACAAE3-UK GX, 80 PLUS Bronze, 85% Eff', SLI/CrossFire, EPS 12V, 120mm Fan
Hard-drive: Samsung 1Tb Spinpoint F3 Hard Drive - HDD
Disk Drive: Sony Optical DVD Writer, AD-5260S-0B, SATA, Black, OEM

Cost with Z68 Motherboard: £344.40
Cost with P67 Motherboard: £340.78

So the components I'm unsure about are the CPU and the GPU.
I am going to go with a Sandybridge build, I was going to wait till bulldozer but I've been waiting ages and don't want to wait anymore.
So the question is i5 2500k or i7 2600k?
Obviously the i7 has hyperthreading but I would like to spend as little as needed.

i5 2500k: http://www.scan.co.uk/products/intel-core-i5-2500k-unlocked-s1155-sandy-bridge-quad-core-33ghz-gpu-850mhz-6mb-cache-95w-retail
i7 2600k: http://www.scan.co.uk/products/intel-core-i7-2600k-unlocked-s1155-sandy-bridge-quad-core-34ghz-gpu-850mhz-8mb-cache-95w-retail

For the gpu: The 3 cards I am split between are the radeon hd 6970, gtx 570 and the gtx 580. The 6970 seems to be sold out everywhere I look in the UK so its probably more then likely going to be the 570 or the 580?

Which out of these 570s are the best? http://www.scan.co.uk/shop/computer-hardware/all/gpu-nvidia/nvidia-geforce-gtx570-pci-e-(480-cores)

Which out of the 580s under £400 are the best? http://www.scan.co.uk/shop/computer-hardware/all/gpu-nvidia/nvidia-geforce-gtx580-pci-e-(512-cores)

This also adds the question, is the most expensive 570 better then the lowest 580?

I am happy spending in the £800+ but £900+ is pushing it a little bit but I can afford it.

So my question is... If you were in my position what cpu would you get and what gpu?
If you think I should get the i7 and the £400 580 because that is the best at price/performance, I will.

Please note, I am not a fanboy of any brand and please take into consideration the games I have listed that I would like to play on max with good fps.

Ps Sorry for this large thread but I would like to give you as much info as possible to help you, help me

 

[wintermint]

I prefer the i5-2500k, you can overclock it easily and yes it won't have hyperthreading but it's not the end of the world.

I find EVGA to be reliable, have good warranty [lifetime unless im mistaken] and they also have a step up program that you should take a look at. I don't know if it's the same in europe.

I would try to change the power supply to something by Antec or Corsair. If you're able to find Seasonic, they're really good. They're the OEM manufacturer for Antec, Corsair, XFX and sometimes OCZ I think.. Just go with Antec/Corsair/XFX

 

[BenIsLegend]

Thanks

Got anything to add about the graphics card?

Ps sorry if I have double posted, I have crappy internet where I'm staying

 

[wintermint]

570 and 580 are good cards. I do prefer to go AMD because it's more budget oriented well I'm a college student so can't blame me The 560 ti works really well too. If you want better performance you will have to stick with nVidia.. If you are price-conscious.. then AMD is the way to go. You can always flash the 6950 to a 6970 if you look it up.

Here's a benchmark from anandtech. You should compare the 6950 to 560 ti. You can also do single comparison for the 570 or 580 but it's better to compare to AMD to see how you could save and still get enough performance to satisfy. Hope this helps.

 

[BenIsLegend]

A friend of mine said to play all new games coming out on max I should get a 580 or 570 or 6970.

I was looking at getting a 6970 but they are all out of stock in the UK so thats why I was focusing more on Nvidia as they are all in stock