So, basically I'm deciding between building (it would be a first time build) or buying...
so.. Build (minus some things to bring it down e.g SSD, Fan controller, After market cooler.. these are all things i can [i hope] install at a later date) ?
http://uk.pcpartpicker.com/user/xFargy/saved/4hgE
or buy..something like this, or around this price..
I recommend building it yourself. When you do your own build, not only do you decide everything going into it, but you know exactly what you have. Plus it is a good experience.
GPU's pretty weak... mobo is awful... not a big fan of the Corsair CX or RM series... I like their TX line and better, but they're generally expensive... no need for thermal paste... or a fan controller for that matter...
http://uk.pcpartpicker.com/p/3yV4v
This is a 40 pounds more... and doesn't include a DVD drive, wireless card, fan controller, or thermal paste... what it does include, however, is much better quality parts... (better CPU cooler, MUCH better mobo that can support an 8-core CPU, less failure-prone HDD, MUCH better GPU, better case, MUCH better PSU)
I don't ever put DVD drives in my builds anymore... they're pretty unnecessary at this point unless you're burning CDs... thermal paste is completely unnecessary, as all CPU coolers come with thermal paste (thermal paste is thermal paste, some people make big deals over nothing, using "good quality" thermal paste might save you a half a degree)... there's plenty of fan control options on the Asus mobo/software suite... the wifi card you might need if you can't hardwire to the internet...
Basically.. this is just all good quality hardware that will let you game properly and upgrade without having to switch out the whole system...
First of all that "KILLER GAMING PC" is not worth it. Particularly, that r9 250 is very poor value.
Drunken Panda's spec seems good to me. However, personally, I would save myself the £30 from the cooler, and get a AMD 8320. Then when you are not happy with the performance later down the road, get a better cooler and Overclock it.
I'm not going to debate whether the extra 2 cores are needed, but at least you will a bit more 'future proofed' for only £30. Logan has said before, the 8350 is ridiulously good value for money. I reckon the 8320 would be too, especially if you get lucky and get a very Overclockable one.
Anyway, I would recommend DrunkenPanda's build (http://uk.pcpartpicker.com/p/3yV4v). If it is too pricy for you, I have attempted to cheapen it up but keep the performance.