I now have an "old" nVidia 8800 GT 512K card and I have just seen an ATI 4850 1Gb with passive cooling at a very good price.

So I have a couple of questions before updrading:

a) Is the image quality of ATI cards on par with the image quality of Nvidia cards for this game?
b) Is ATI 4850 1 Gb faster than nVidia 8800 GT 512 Kb for this game?.

Regards. Thanks in advance.