Currently I have a 9800 GT running two monitors, stably. But I wanted to just add a small, 17" monitor so I can triple monitor, but only have two DVI ports. Could I just install a ATI Pci video card and triple monitor and potentially quad monitor? Or should I just buy usb to dvi?
It's easier with a same make PCI card for the drivers.
USB is a solution, but it's slow refreshing and won't support all the features on it (some flash, some media playback features disabled). It's really a last resort and only if you can't make the other work.