I just finished my prototype for a unit to allow a computer (PC) to operate a radio controlled airplane. I really should take the time to make a proper post here, but time isn't something I have a lot of right now, so for now I'll just point to what I already have.
I hope someone out there finds this useful.
Hardware: http://cheshirekow.com/blog/?p=236
C++ Class for interfacing with the hardware : http://cheshirekow.com/blog/?p=288
Program for determining the saturation points of actuators : http://cheshirekow.com/blog/?p=305