Advice/help on my first build please? Thanks

[Awqaw123]

I'm trying to build my first custom desktop and these are the current components I've picked out. Please tell me of what would be good to change/downgrade/upgrade. Thank you. (Also please tell me if these compnents are compatible)
Motherboard: http://www.trademe.co.nz/Browse/Listing.aspx?id=568675818
RAM: http://www.trademe.co.nz/computers/components/memory-ram/1-gb-or-more/auction-568337273.htm
CPU: http://www.trademe.co.nz/Browse/Listing.aspx?id=568669650
GPU: http://www.trademe.co.nz/Browse/Listing.aspx?id=569587063
HDD (I already have a 3tb extHDD): http://www.trademe.co.nz/Browse/Listing.aspx?id=567962198
And I was thinknig of a 550w power souce. Would that be enough? Anyway thanks again.

 

[aa-4123]

What is your budget?

 

[Awqaw123]

Im trying to keep total cost of components below 1.2k. Asi, is there much difference between the 7950 and the 7870? Ive also asked on other websites (4chan's /g/) and they told me my CPU was garbage. Is this true?