The Xbox360 controller is supposed to work out-of-the-box.
Download the drivers for this pad, plug it in, switch in on and then start the game.
xbox 360 Drivers: http://www.microsoft.com/hardware/en-us/d/xbox-360-wireless-controller-for-windows
Choose your OS on that page.
I operate my PS3 Pad in "Xbox360 Emulation mode" - no problems, yet. Even Wireless over Bluetooth.
PS3 Pad Driver: http://www.motioninjoy.com
I use 6.0.5
Xpadder is a solution, but you will lose analog controls.
Playing digital with an analog stick feels creepy, so in this method you are stuck in digital mode.
You will emulate keystrokes then.