Games are more heavily reliant on graphics card and anything above the amd phenom II x4 955/i5 760 is not really necessary for gaming and either of these processors should last you a long time to come. Given what else you plan to use your system for I think if you're looking to spend towards the top-end of your budget, then more invested into the graphics card (and therefore better gaming performance/longer lasting) and the addition of a solid state drive would be more beneficial to you than spending a considerable amount more on the i7 950 cpu/mobo and getting a less powerful graphics card (and so lesser gaming performance).
So here you have the amd path covered (should you prefer to go intel then you'd simply swap the cpu for the i5 760, the mobo for an socket 1156 intel mobo).
-The more powerful gtx 470 is included here, which gives a very decent performance boost over the 1gb 460 (and you get mafia 2 thrown in).
-A cracking solid state drive (sata6gb/s). They are really popular at the moment. You have your 1tb hd included in this build for most of your games, music and other programs, but on the solid state drive you install windows, whichever internet browser you use, one or two of the games you play most regularly (or those which put the most strain on your system in terms of load times) and these programs will load incredibly quickly.
-A great motherboard which supports sata6gb/s (which is the fastest speed available for your ssd), usb3 and crossfire should you decide to use two ati hd**** cards in future.
-4gb memory is plenty for gaming and these patriots have low cas7 latency.
-CM90II adv is a corking case! Great looking, excellent cooling with its 3 (very quiet) fans, tool-less.
-Excellent cooler in the titan fenrir evo which will keep your cpu running nice and chilly and will allow you to overclock either cpu should you want to.
If you're looking to spend the maximum of your budget then frankly, I believe for gaming this would be the better option over the £1000 i7 950 specced earlier. You're getting a more powerful graphics card (which should last longer also) and a brilliant solid state drive which will improve load times (windows, whichever games you put on there) considerably.
