Building a new Gaming computer and need advice

Hello I am going to be building a computer in the next month or so and have had a few ideas, But need advice on parts.

Here's just some general info so you can help me:

Im in the UK

I would prefer it from amazon.co.uk

My Budget: £800 (would like to go less)

Usage: Gaming

Overclocking: maybe if its easy =] (Im completely noob)

SLI: eventually when I have money

The parts I have thought about so far:

MSI NVIDIA GTX560Ti OC 880MHz 4200MHz 256Bit DDR5 TWIN FROZR II Graphics Card (1024MB, PCI-E, 2xDVI, 2xHDMI)

Corsair CMZ8GX3M2A1600C9 8GB 1600MHz CL9 DDR3 Vengeance Memory Two Module Kit

Sony AD-7261S-0B 24x Internal DVDRWRAM SATA Black Lightscribe

Arctic Silver 5 3.5g Thermal Paste

LUPO Anti-Static Wrist Strap Grounding Wrist Strap/Band

Microsoft Windows 7 Home Premium with Service Pack 1, 64-bit, English

Intel Sandybridge i5-2500K Unlocked Core i5 Quad-Core Processor (3.30GHz, 6MB Cache, Socket 1155)

Seagate ST500DM002 3.5 inch 500GB Hard Drive (Serial-ATA, 6Gb/s, 16Mb, 7200RPM)

AsRock Z68 Extreme3 Gen3 Motherboard, Socket 1155, PCI-Express 3.0, DDR3, USB 3.0, HDMI, 7.1 HD Audio, ASRock Instant Boot

NZXT Crafted Series HADES - Mid tower - ATX - no power supply ( ATX12V 2.0 / PS/2 ) - black - USB/Audio/E-SATA

OCZ OCZ-ZS750W-UK ZS Series 750W 80+ Bronze PSU with 135mm Fan & single +12V Rail

Cooler Master Hyper TX3 Cooler

Links:

http://www.amazon.co.uk/MSI-GTX560Ti-OC-4200MHz-Graphic...

http://www.amazon.co.uk/Corsair-CMZ8GX3M2A1600C9-1600MH...

http://www.amazon.co.uk/Sony-AD-7261S-0B-Internal-DVDRW...

http://www.amazon.co.uk/Arctic-Silver-3-5g-Thermal-Past...

http://www.amazon.co.uk/LUPO-Anti-Static-Wrist-Strap-Gr...

http://www.amazon.co.uk/Microsoft-OEM-software-intended...

http://www.amazon.co.uk/Intel-Sandybridge-i5-2500K-Quad...

http://www.amazon.co.uk/Seagate-ST500DM002-500GB-Serial...

http://www.amazon.co.uk/Z68-Extreme3-Motherboard-PCI-Ex...

http://www.amazon.co.uk/NZXT-Crafted-Series-HADES-suppl...

http://www.amazon.co.uk/OCZ-OCZ-ZS750W-UK-Bronze-135mm-...

http://www.amazon.co.uk/Cooler-Master-Hyper-TX3/dp/B002...


Please can you tell me if this build would be good for Battlefield 3, Skyrim on high and if its future proof.

Also can I see your opinion on if I should get a better graphics card and downgrade to maybe a less expensive AMD processor?

Also is a 3rd party cooler necessary?

Is it compatible?

Thanks in advance (as you can tell im a noob)

btw sorry for the big post ( I tried to make it as clear as possible)