Nothing puts a smile on a gamer's face like the smell of a brand new graphics card. The ability to see the sweat trickle down your opponent's face while you pump him with shotgun rounds can only be captured if you have a graphics card that's powerful enough. But, most of the time, a graphics card is seen as an extra investment, which it is to some extent, so why buy it?
Why should I invest in a graphics card, what about my onboard graphics?
Well, quite frankly, onboard graphics only meet the minimum requirements of a game, which means you can play the game, but the experience wouldn't be very enjoyable. If you only plan on playing Solitaire, you need not read further. Now-a-days, with Nvidia promoting CUDA and ATI coming out with their Stream technology, your graphics card is being used for more than gaming, such as for applications like video encoding (Badaboom and AVIVO), physics processing (Nvidia's PhysX), and multimedia features like Photoshop CS4, which supports hardware acceleration.
Instead of pointing out the features you should look for when you go card hunting, we've defined three categories/characters of gamers, who have completely different mindsets; it's up to you to figure out which category you belong to.