http://www.overclock3d.netJust to put things in perspective.
Look for their video channel and find the video on how to build a gaming rig for under 600 pounds (sorry american keyboard, no pound key). Just enter "how to" in the search box and it should be the third video from the top.
It may not be what you want to build, but it calms the nerves a lot regarding having the hottest hardware on the market and how to make choices, you can do great things without the highest priced components.
With all the new stuff coming out in a little while and for pcs in general it is very easy to get caught in the rat race for the latest and greatest hardware.
I know that is not an answer to your question, however my point is you can buy whatever you want right now and you look a month later on an internet retailer's site and say to yourself, man, I should have waited another month or two and that will go on and on.
As for AMD, the bulldozer/FX processor is coming out and new AM3+ MBs are available and even now that these MBs have just been released, I read on another sites techsection they will be obsolete pretty soon as well, since a new socket is due to come out for the bulldozer.
Whatever you do you will feel as if you missed out on something.
So if you feel like an i7 or i5 go for it and do not worry about the rest, if you feel like a new gpu is in order go for it and there is always a little later to upgrade other things.
It seems to me when you have your own build it always remains a work in progress, so see what's in the budget, go for it and there is always later for the other stuff
.