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Or you could just go for the OC edition - save £20 or so - they both overclock to around the same max and the OC will do OCX clocks easy unless your really really unlucky.
Get the zotac 260 for £207 and overclock it yourself.
All the reviews I've seen so far show dead space running far far better on the 260 maxcore than the 4870 - in some cases as much as 50% faster.
The 260 maxcore right now is also the best value for money GPU (if you compare 180.60 v 8.12 drivers).