Which GPU?

[PMol]

I need to choose a GPU for my new system. My specs are......

Intel Core i5-3570K 3.40GHz (Ivybridge)
16Gb GeIL EVO Leggera DDR3
Gelid GX7 CPU Cooler
Gigabyte Z77X-D3H
Intel 330 Series 120GB 2.5" SATA 6Gbs SSD
Seagate Barracuda 7200.12 1TB SATA 6Gbs
Antec 900-2 Case
Jeantech Storm 700W PSU

My budget is £200. I don't mind AMD or Nvidia since I have owned both in the past and been quite happy with either. I read the article about overclocking a 6950 to a 6970, is this a good option? Or shall I go for a 7900 series? I have literally no idea what would be the best GPU to compliment my system. My computer is on 24/7 as it streams media during the day, plays games in the evening, and movies at night. So I don't want any overheating issues. I had a card overheat and die before, and up until yesterday when I rebuilt my system (Here!) I was using a Vortexx Neo cooler on my HD4870. Is it worth spending £150 of my budget on a GPU and the other £50 on a decent GPU cooler??
I play a lot of games such as Battlefield3, EVE Online, Command & Conquer, and I use a 24" monitor (if that makes any difference).
Thanks.

 

[PMol]

So everyone seems to be leaning toward the 7850. How do they deal with temperatures? Do they have sufficient cooling? My HIS 4870 didnt. It was noisy as hell and still reached 90c under load. Would I need to fit an aftermarket cooler before overclocking? I like the gelid one.
Also regarding my PSU. I've had it for 3 years running 24/7 and no problems whatsoever. I won't be replacing it yet.

 

[PMol]

OK It's decided. I'm gonna get these 2 items, and that should finish my system.
http://www.overclockers.co.uk/showproduct.php?prodid=GX-157-MS&tool=3
http://www.overclockers.co.uk/showproduct.php?prodid=HS-002-GD

The cooler will go nicely with my CPU cooler. Thanks for the advice.