Do you need more than one graphics card? Absolutely not. But if you're looking for better performance and you want to save some money, using multiple cards at once via SLI or CrossFire will afford you better performance than simply swapping out your solitary card for a better version. There's one more angle to consider: keeping your upgrade path open. If you're buying a new PC (or ) and have room in your budget, getting a pricier card up front will give you room to maneuver later on, whether you're adding more PCI-dependant hardware, or foresee picking up an identical high-end card later on.