Upgrade help (please)

[GlacierMint]

Morning everyone

Bit of a speculative one, bought a PC 3 or 4 years ago and I'm starting to think about upgrading the graphics cards. What's the most practical upgrade to a pair of ATI Radeon HD5870's in crossfire? I'm looking for a decent performance increase, but I'm not looking to blow a fortune (funds aren't what they once were)!!

Doesn't need to be Crossfire if a single card is better. Oh, and I'm clueless on the latest cards!!

BTW:- running an i7 960, 12Gb memory and Win7 64bit if that makes any difference.

 

[GlacierMint]

Cracking, thanks gents.

Will one of these be faster than the two 5870's or am I going to need to get two?

I'm guessing the Twin is the way to go (given that it's cheaper on offer)?

I've also found that the m\board I've got is a bit of a bodge, it's an Intel P55 Express chipset which claims PCIe 2.0 but only at 1.0 speeds. Anyone know if this going to be a big problem?