HCL is the Hardware compatyiblity list here. It is a tab up top of this site. It has a list of a lot of hardware and how people have faired using it with Linux.
Sounds like they work though so....
You are sure your cards are seated securely. You are sure your second monitor works. Cables all work?
Do you have access to download another live cd? Get the live DVD iso and burn it. from here:
SUSE should be able to get it right.
From KDE go to terminal and open the file /etc/X11/XF86Config-4
you can do this with:
a more gui experience --> kate /etc/X11XF86Config-4
If you have a printer connected print a copy.
If not cut and paste it to a doc you can email to yourself to scrutinize later.
You are looking just to get a working xserver config file.
I apologize. I have not had to do this for a while.
Try SUse let me know what happens.
In SUSE you can use YAST to set up multiple monitors.