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What should I choose? I am on a bit of a budget but if the GT is really worth £50 more I will get it.

it's a well known fact that both ATI and Nvidia suck at Crysis
Fixed.
it's a well known fact that Crysis sucks

I did some benchmarks and it seems like my GT @ 700/1800/1000 is 10fps in crysis faster than a 3850 clocked to 1Ghz core but then again I only had a duo at 3.4 whilst the guy with the 1ghz 3850 had a q6600 @3.6.