um...warping your rotors, wont cause you to shake like that all the time even at high speed. warped rotors, cause your car to shake only when you brake, and thats the steering wheel, not the car, i know how this feels because my parents had warped rotors on one of they're cars, and i tested it out. either its your tires that are out of balance. or you may have a bad halfshaft. those are only things that come to my mind. (i had a bad u-joint in my driveshaft and it made my whole car shake like it was giant vibrator, not that i know what one feels like)
edit: i love that sig citrix....made me laugh.