Soldato
Would it be worth me getting a HD7950 rather that a HD7850?
This shows a comparison so you can decide
http://www.anandtech.com/bench/Product/550?vs=549
So in the checkout at the top of the page i have storage and this SSD which do the same job?
Yes essentially they do. But the SSD is really good as a boot drive [i.e. it'll have Windows on it] as it'll decrease boot/loading times, then the hard drive is just for storage as a 128GB SSD can fill up quickly
With your budget I wouldn't consider a build without one to be honest.