I had this problem to
First of all, XWA think it is an actualy rudder pedals on the joystick... so you need to go to the option screen (hit escape while in XWA) select game controls, and turn off the rudder
Now that that is done, you can use the Wingman Profiler program to adjust the senstiviy, and the dead area. I usually turn the senseitvity waaay down, and turn the dead area waaay up.
This should solve all problesm, also you might want to fly a few mission to get used to a rudder. I noticed i like to twist my wrist a lot whle trying to do exteme turns