Need advice on component compatibility (first build)

All good but the PSU. I'd change it to a VX450W or a Seasonic 520W.

Get the 6870 if budget allows, and change the PSU.

Check out pcpartspicker.com For the most part it only lets you choose compatible components for your build. Overall I think you did really good, here are my suggestions.
1) Might want to get a 990FX MB it allows for PCI express 2x16. That way you can get a second Vid card later on and get the x16 on both cards.
2) OCZ is selling a 750W PSU for $50 after rebate on newegg.com
3) Might want to look at the 7870 video card.
4) After awhile look at getting a SSD Drive, really fast for not much cash.
Its always easy to make suggestions

I didnt convert 700 Euro to US but here is a build at Pc parts picker http://pcpartpicker.com/p/f3fV (note I did not add a Network card)

Thankyou for your time and replies,

Taking into consideration what you fellas have said i have changed the PSU to a OCZ ZT 550W. but to be honest I dont really know why im doing this, is it because of the brand or was it the wrong wattage ?     thanks

I definitely cannot afford a 7870 but could maybe stretch to a 6870 but still might end up sticking with the 6850  
I have changed my motherboard to the ASRock 990FX as it is only slightly more expensive  
And at the moment I cannot afford an SSD but will surely invest in one in the future.

so my build is now :

cpu processor: AMD Phenom II x4 quad core 965 black edition
graphics card: MSI HD6850 GDDR5 PCI-E (or possibly the) XFX HD 6870 1024MB GDDR5 PCI-Express Graphics Card
motherboard: ASRock 990FX Extreme4 AMD 990FX (Socket AM3+) DDR3 ATX Motherboard
power supply: OCZ ZT 550W '80 Plus Bronze' Modular Power Supply
hard drive: SEAGATE BARRACUDA 1TB SATA-II
ram: KINGSTON BLU 4GB DDR3
optical drive: 22x DVD±RW SATA ReWriter
wireless card: Asus PCE-N15 300Mbps 802.11B/G/N Wireless PCI-E Network Adapter
case: BitFenix Shinobi USB3.0 Gaming Windowed Case
OS: windows 7

i used the pcpartpicker link sikkoB suggested (thanks) and it seemed to think these were all compatible  

If my PSU was wrong because of the wattage then the replacement ive chosen is no better, haha   if someone could clear that up for me that would be great.

That PSU (Akasa) is unknown to me, and you should stick with a more well-known/reliable brand. You don't want an unreliable PSU because it can bring down your entire PC. Don't want your £700 purchase going up in smoke do you?

haha definitely not. that seems wise thankyou for the good point. OCZ seems pretty well known ill go with them.

If you need any more help just ask.