You don't need 16GB of memory, especially for a gaming rig. Get 8GB, put the extra money into an Intel platform or better video card. Either will give you better performance, while 16GB vs. 8GB is literally no difference for the vast majority of uses.
For sure do not get the 4000 series go with 6000 at a min 6100 or 6200 even then like other poster intel is the way to game right now. On video card 6950 or 560 Ti is the min i would go and these will be out dated by end of year when the 8000 and the 600 series come out...
ok for the ram found some 1866 2x4gbs what is with the cpu? is it not stable it has a blazing 4.2ghz and a decent bus speed, for the gpu i'm confused the sapphire 6870 destroys most 7000's what is better cause i sertenly don't have the money to crossfire and the i3 isnt sandy bridge so it doesn't boost memory distro? for 500£ what is a good setup?
I'd strongly recommend 1600 with low latencies. It will cost less than 1866 and perform just as well.
what is with the cpu? is it not stable it has a blazing 4.2ghz and a decent bus speed
There is a LOT more to processors than clock speed, and the bus is totally irrelevant. Clock for clock, AMD chips are dramatically slower than Intel chips. They try to compensate by adding more cores, but this doesn't help most workloads. Intel is a much better all-around choice, as well as being faster at just about any given price point.
for the gpu i'm confused the sapphire 6870 destroys most 7000's what is better cause i sertenly don't have the money to crossfire
The 6870 is good, but if you're just moving around money in the build the new 7000s launching soon (already?) are a bit better at roughly the same cost. I forget the model numbers, haven't been paying much attention since I just snagged a 6950 myself.
and the i3 isnt sandy bridge so it doesn't boost memory distro?
Huh? There are plenty of Sandy Bridge i3 models to choose from, and I'm not sure what you're talking about with "memory distro."
An i3-2100 is a very strong cheap gaming CPU. If you want some more horsepower, the 2500k is very reasonably priced and will be enough for literally any game on the market, probably for years to come.
The 2100 is going to be plenty for most games, though you'll have noticeably worse performance in some games than with a 2500k. Multiplayer FPS games hit the processor pretty hard (more players means more load on the CPU), and Skyrim is notoriously CPU hungry.
I'd recommend you look through the latest Best Gaming CPUs For the Money article here on Tom's. They point out the processors that provide the best bang for your buck at each price point, and explain their choices. It's a very handy article if you're a novice builder and want to get the most out of your rig.