Rob, it depends on the video card; there are both AGP and PCI versions available. The AGP versions are faster; mine is a flashed Nvidia GeForce 6200 AGP that I bought from an eBay vendor for $85, and which works fine. Yes, you remove the old video card, and replace it with the new one. Check to make sure that the card you choose will support your display's interface, VGA, DVI, HDMI, or S-Video. Also, be sure that it will support dual monitors if you want that capability, and that with the correct connectors. You can usually adapt between VGA and DVI, but HDMI is more difficult. - Michael B. in Cincinnati