How do I get my computer to see the new video card?

I have a Emachine T3304 that has a failing on-board video card.(but still somewhat works) I bought a new 256MB PCI-E video card to install and get working before I had a total failure of the other but the computer is not seeing the new card. I tried looking in bios to disable the on board video but don't see any option like that to choose. Does anyone know how to go about doing this?|||It HAS to be in the BIOS. You just need to look a little more carefully.