Physically, it's possible to have more than one of those cards in one computer. However, they will not be able to work together. If you want two cards to work together, they must be of the same brand, and same or similar chipset. Even then, this is only allowed on some cards, usually not lower end. Look up Nvidia SLI or AMD Crossfire for more info.
If you do get another graphics card in there, you'll be able to connect more monitors, but they won't co-operate to increase your framerates. I would just remove the 250X and upgrade to the better card, assuming the rest of your system is up to spec.