Processing signals sent from Arduino to Game Boy Advance Emulator.

I am trying to create a USB Joystick to control Visual Boy Advance emulator. I know how to get button push events and how to send a signal to a computer via USB. I just need a way to interpret this signals on a computer to something like key presses on a keyboard. How would I do this? I am guessing that I would need to create some sort of windows driver.

I am guessing that I would need to create some sort of windows driver.

I think that if you had a clue how to do this, you wouldn't need to ask.

What is this "Visual Boy Advance emulator" that you want to control? Perhaps it has a way of reading data from a serial port, already.