pretty much any NVidia card blows away all ATI cards if you ask me.
I was playing CoH for a while and the only machine with an ATI card failed, might be 5 min into the game, might be 2-3 hours into the game but on average it was 30 min.
I used about 10 different driver versions and all failed.
it didn't matter if I used 1 or 2 cards, crossfire enabled, disabled, one card only, the other card only.
all of my problems went away when I threw those ATI cards into the trash can and bought a relatively cheep 460 NVidia card, which is able to run CoH on that particular monitor at 60Hz.