Well I decided that warranty is very important to me, so I chumped the extra £20 and bought the 7950 Windforce from Gigabyte. Plus, after measuring my case it appears as though the HIS 7950 is a bit of a beast and would take up almost 3 slots!
The 7950 Windforce looks to be just a little bit longer than my 5850, so that coupled with the 3 year UK based warranty justified the extra £20, just wish I had of bought a few weeks back when they were selling for only £249!
Watch it go on special sale tomorrow haha.
Really looking forward to seeing how it fares to my 5850 that I just sold on ebay for £80. I still can't believe what an amazing card the 5850 was, I had it since December 2009 and it has played everything at great frame rates and if I wasn't so obsessed with Planetside 2 I would probably have kept it for a bit longer! Was a bit sad actually when posting it to the new owner lol.