For running a dual monitor setup you could try the Y type adapter as long as the card itself supported it. That wouldn't be anything good for gaming but for expanding a basic desktop. Generally plan on something similar to an SLI setup without onboard video.
You have to disable that to run an installed PCI-E or AGP card anyways. Without SLI you are looking at one AGP card and adding in a PCI type card there to support a dual monitor setup. As for the vga driver as well as other updates for that model board the support page at Gigabyte is where to look. That is a quick trip to GIGABYTE - Support - Motherboard - Driver