Disable on board Video

Usually, you would have to set a jumper to disable the on board video.  Check your m/b's manual for details...

There can be 2 ways to disable your Video Card. First as larbel already mentioned there could be a jumper on your mainboard. Second, many bios allow to switch of the card in the CMOS-Settings. Enter the CMOS-Setting and search for such a flag.

I'm sorry, I should have included that my computer is second hand and does not have its documentation.  
How do I know whether the on board video is disabled through the BIOS settings or by a jumper on the motherboard?
How do I locate the correct jumper to remove on the PB680 (Intel NV430VX Orlando) motherboard?   I have located what I believe is the jumper bus but have no way to know which jumper I should remove.  I have attempted to look at the Intel and Packard Bell web sites but I am afraid I lack the experience to be confident I understand the information there.
Thank you for your help.

Even though you didn't buy the computer from Packard Bell that doesn't mean that Packard Bell shouldn't give you customer support and tell where the jumper is. When I have been in your situation, I just took some paper and physically illustrated the mother board and the jumpers (at least in the area I wanted to adjust) to make a "copy" of my MB's configuration. Following, I would adjust the jumpers and start my system to see if my changes were successful. I could always return the MB to it's previous state from my drawing. For your reassurance: it should only be a jumper or BIOS change that needs to be made to disable your on board video card.