i have an nvidia 9500 gt pci video card, but, my motherboard also has an on board graphics card. So my question is, does it matter if i disable or enable the on board graphics? Does it help if I enable it?, since my monitor is connected in my pci vid card.
Most current motherboards will disable on board graphics automatically, you should disable it in BIOS though.
Short answer to your question, is NO, you won't be able to use both. It is an either/or proposition.
On some ATI chipset boards they have "Hybrid Crossfire" enabled boards that will use specific ATI videocards with the on board video. I have one, but I have a much better video card, so I don't use this option
So if the PCI-e 16 slot is populated, the motherboard will disable the onboard video, and use the graphics card in most cases.