You probably won't want to use the onboard video (the other VGA connector on the motherboard). Instead, you want to use the DVI connector on your video card. It's the white one. To do this, you'll need to use a DVI to VGA convertor, which is often included with video cards that have both types of output. It looks like this:
http://www.newegg.com/Product/Produc...82E16814999901