2 x HD5870 vs New Card?

Hello Toms, My Computer Specs should be in Sig. I am coming into money for my Birthday (around £200 ) and I'm wanting to update my Computer a little bit. My single HD5870 still maxes out most games I play on my single 1980 x 1080 monitor. However I noticed that in some recent tittles such as Sleeping Dogs and bf3 it is starting to struggle if I want to fully Max out these games. It happens mostly on games with dx11.

I want to upgrade graphics and I'm not that up to date with the recent card releases and BenchMarks. I am wondering if I would be best to crossfire my HD5870 or Buy a new later series card (Preferable a Radeon card?

Lastly, In my personal experience I notice that Radeon but a lot higher recommended watt power supply than what you really need. I am wondering you think it would be ok to run crossfire on my current PSU ( see in my Sig ). I put my system through a psu calculator and it recommended 530watts. Would it be safe?

And do you think that my CPU would bottleneck a new more powerful card, or X-fire HD5870's

Thanks