I have a Dell XPS 400 that is about 4 years old. My Nvidia Geforce 6 series graphics card died and has to be replaced. I went onto dell's site and bought one of the graphics cards that they recommended for my computer, the VisionTek Radeo HD 2400 Pro. However, it won't fit into the pci slot. I really really don't want to replace the motheboard. What graphics cards can I get that will fit into the same slot that the Nvida was in?