I havew under a list of components I would like to buy and I want to make sure im getting the right components which all fit together and can work well for what I need;
http://www.amazon.co.uk/gp/product/B00608M09K/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=A3P5ROKL5A1OLE case http://www.amazon.co.uk/gp/product/B003N8GVUY/ref=ox_sc_act_title_5?ie=UTF8&psc=1&smid=A3P5ROKL5A1OLE RAM
http://www.amazon.co.uk/gp/product/B0088PUEPK/ref=ox_sc_act_title_5?ie=UTF8&psc=1&smid=A3P5ROKL5A1OLE Hard drive
This is what i put together. It'll perform beastly in gaming as well as rendering. However if you prioritize editing before gaming, i would switch out the 660 ti with a 660, and the 6300 with an 8350. That way it'll still be a beast of a system, but have a bit more juice for the editing stuff.
Also, if you are willing to go a bit over budget, or sacrifice something, i would go out and buy an aftermarket heatsink. The temps are okay with the coolar that comes with the CPUs, but they make a lot of noise. However if you don't care about the noise that shouldn't be a problem :P
But when i say it's noisy i mean it is VERY noisy (At least the 8350 fan i've got). Under load when playing games like FC3 Planetside 2 etc it sounds like a plane. So i'd recommend investing in at least an EVO to reduce the noise. Of course you could just drop the aftermarket fan and order an aftermarket fan if you find the noise annoying after a while.
you can cheap out under 600 pounds if you change the cpu to a FX6300. or FX6350, but i choosed for the 8 core. further i pickedup a 7870XT faster in gaming then most 660ti´s and for sony vegas it has open gl support. to bad that you cant push your budget up to 650 pounds otherwise i had put in a Asus M5A99FX pro R2.0 that has a better power phase 6+2 could give more oc potential to the 8 core.
I would stick with the 660 TI over the 660, more CUDA cores, but that's dependent on what editing software you use. AFX screams with CUDA accel enabled.