Well from what your saying it seems you want to employ one of the forum members to build a pc for you, well im afraid this cannot be discussed in this forum due to the terms and conditions of the forum,
We can only give recommendations to you,
My advise would be to look about on some online stores who can tailor a pc to your needs.
But for £500 you will have to make a few sacrifices if you want to play the latest games.
I would recommend waiting a few more months until you can get a bigger budget,
if you really need it soon though im sure other forum members can offer up some good deals on base units,
Im afraid hardware isn't one of my strong points.