To not experience any VR sickness with the state of today's technology, you must either be using exclusively the tame applications of the technology -- such as garden walk, home tour, etc, and not trying out any FPS games like TF2 or something -- or you have something biologically off about your linkage between your natural balance sensors and how your brain tries to correlate them with what your eyes see.
Either way, that's good for you, embrace the future more easily than the rest of us :)