Xbox controller on a PC ..

So, tonight at Fry's, I bought this Xbox to USB 'converter'. It says you can use the Xbox controller on a PC with it. I had to get additional drivers from the companies support site .... but in the END ... Yes, I was able to use the Xbox controller on a PC with the PC version of NBA Live 2005.

My question is ... not all of the buttons on the joystick were 'seen' on the PC. The two trigger buttons I think were all that I was not able to get to work. Does anyone know of a way to make all of the controller buttons on a Xbox to USB on a PC work like they do on the console?

Thanks!