One thing to be aware of, most gaming cards are dual slot, meaning they take up the space of the expansion slot next to them too. Your computer has 3 slots, one of which is for the videocard, but is also using one of the other slots for something. If the slot being used is next to the videocard slot, you'll either have to remove that component and figure out another way to do whatever it is it's doing, or find a single slot videocard which seriously limits your choices.