I am trying to set up an older computer (Dell Dimension 8300 with a Pentium 4 processor and 2 GBs of RAM) with a dual monitor setup. KDE 4 is a little slow, but KDE 3 runs fine on OpenSuSE 13.2. However, my dual monitor setup only clones the first display, and there are no options to change the monitor settings. It is using a PNY Vetro GeForce graphics card, if that changes anything.
You might get some joy using xrandr (via CLI) to configure your dual monitor configuration. If you prefer using a GUI, try installing/using arandr
Since it is a NVIDIA video card you did you install the proprietary drivers? If so you should have a nvidia-configure program you can also setup dual monitors there.
That worked for me!
Glad to be of help. 
As gogalthorp indicated, for those using the proprietary nvidia driver, the ‘nvidia-settings’ utility provides a means to configure multiple displays.