Basic Dedicated E-Comm. You may want to consider one if you plan to play a lot of games or if you're used to Sega or Nintendo controllers. I'd recommend getting one but it will add another few bucks to your system price.
Most games work fine with keyboard controls, the mouse, or a combination of the two.
If you want a game controller, you'll have to choose between a joystick or a game-pad. There may even be other alternatives available, but your selection will be limited to what the computer comes with if you buy from the computer manufacturer. I'd recommend buying a game controller separately if you don't know exactly what you want, just because you should really get one that suits your needs. Corporate client PC recommendations Not much to say on this one. Most companies don't need to supply their employees with game controllers.