Nvidia 570 WITH ATI 5450

Hey everyone!

I have a Nvidia 570 hooked up to two monitors (running flawlessly) and I'm trying to get my third (and perhaps fourth in the future) hooked up and running with the ATI 5450. I don't need 3D on the ATI cards or anything - just simple web browsing.

The problem is that I'm not sure how to go about doing this. I know it would involve modifying the xorg.conf, but I haven't been able to get it working. If anyone can toss me some hints/tips or perhaps show me how to do this, it would be much appreciated!