Oh you may be talking about a gameport (wich is not for video, but for older humain interface controllers before the USB age).
So what do you mean by stock? Integraded graphics? Usually intergraded only have one output so you would need to by a secondary graphics card in order to acheive dual-display.
Also, assuming you have PCI-Express and the correct chipset, there are some cards that simply add a DVI port to your computer. It still runs off your onboard video, but lets you have two monitors connected to it. I know the Dell Optiplex GX620's I used at the hospital came with them.