There is no reason to upgrade. The 5770 can handle crysis on the highest settings at that resolution to my knowledge. The only next upgrade I'd see that'd be reasonable is your monitor then your GPU. Otherwise not at all. The 5770 I'm pretty sure can handle Crysis at very high at that resolution.
a tr2 460w? u mean 470w like this one http://www.thermaltakeusa.com/Product.aspx?S=1172&ID=15...
I have that PSU and im pretty sure there is no 460w model.
If it is that model, you should be able to run a 6850 or gtx460, but you will need a 2 into 1 6 pin power adaptor which should come with the card.
Yes i would agree.Crossfiring with another 5770 would be much better than getting a 6850 or 460 and then just throwing away the 5770.Crossfiring with a 5770 should bring you up to around a 5850 level,mayb a bit slower witch would still be better than a 460 or 6850.