Hi,
If you goto IOA you can get yourself ready by riding Cat in the Hat (which twists and turns you pretty hard, (but it's just a flat track, a kiddie ride), then go to the Unicorn (it's a tiny coaster, no upside down turns or even that far off the ground). I am sure you can do that one. And, if you've worked your way up to the Unicorn and found it to be no problem and want to try a bigger coaster my suggestion is the Hulk. It doesn't do the take forever to get to the top of the first hill thing with most large coasters...(chug,chug, clank, clank, clank, oh god it's so high up here thing). This one litterly rockets you straight up to the top (like Disney MGM's Rock -n-Rollacoaster) and then the normal caoster takes over and it was an amazingly smooth ride. However, their are alot of upside down loops and turns on this one. But, if you keep your head back, try and stay calm and relax when the coaster first starts you'll be just fine and having fun by the first turn. I would not suggest Dueling Dragons...this thing doesn't even have a floor...(no bottom to the car) your feet dangle down the whole time and if you ride in the very first car you really feel like their nothing holding you in or on the track. I rode a coaster simular to this at Busch Gardens called Montu and I like coasters and will try just about anything once....well once was enough for me on that type of coaster! <BG>
If you go to Disney you should try Big Thunder Mtn. (cause you can see the track...most of Disney's coasters are Dark Rides) and seeing the track might help you feel a bit more comfortable, plus it doesn't go upside down or do anything real fancy. There is also a cute new one at DAk in Dinoland that spins you and you can also see the track on that one too. My mother said it reminded her of the old "wild mouse" rides at the fairs. I drug her on this one for Mothers Day recently...lol!.
Anyway, just have fun and enjoy....these are just my suggestions for you....
Mmketeer