Although using an xbox controller on a PC shooter is tantamount to BLASPHEMY!
Officially PC BFBC2 doesn't support xbox pads on the PC, there are ways of doing it, but they're messy. The two issues are the triggers on the pad count as one axis and EA decided not to allow users to manually delete the joystick bindings as you could in the Beta
Caveats: The following is messy and buggy. It will set the game up for xbox controller only e.g. you can't simply switch back to mouse and keyboard without switching the config files back to the original (requiring restart of game)
Let the mess begin!
Open up your My Documents folder, navigate to the BFBC2 folder and open
Look for a folder named "INPUT". Right click on the "INPUT" folder and rename it to something e.g. input-bak The input folder contains all of your controller setup, essentially you've cleared the all the controller settings.
Next have a look on google for a tool called Xpadder (possible expadder) and joy2key, (http://www.instructables.com/id/Use-an-Xbox-360-controller-as-a-mouse/step4/JoyToKey-Basics/) (which coincidentally is the same tool used to fix joystick hat look in bf2)
Essentialyl what you're doing here is mapping keyboard and mouse controls to an xbox gamepad