At the risk of being a "Ditto" poster. I would heartly agree with those that are telling you to "follow the directions" on the ride. I went on this ride multiple times last April. I was only affected by the ride the one time I decided to test the G-Forces by lifting my head off the seat back.
Head back, eyes forward at the screen is the way to go. Everyone's nausea level is different, but I found that if my head was back and eyes were forward I was fine.
Also, in case you have not already found out, the intense spinning only happens at one or two points of the ride, not the entire time. Of course if you are prone to motion sickness, then all you need is once, I guess.
Personally, I would recommend this ride as a must see. And I would agre with the people who say that kids appear to be less prone (in general) than adults. My son went with my wife and I'll give you one guess which of the two came off a little "green around the gills".