You will have no problems fitting in the rides! I weigh a lot more than you, and just got back from Disney World. There are big - I mean really big - people all over the place at Disney, and they were all having a blast, just like me.
For pictures and descriptions of Disney rides, go to Deb's WDW at Large:
www.wdwig.com/ridsiz.htm
There are comments from lots of people and their experiences. And a whole list of rides that have low bars, high bars, bench seats, etc. Then go to the "home" page for lots and lots of Disney info, unrelated to size!
Anyway, this is my 4th time at Disney, and have always weighed more than you! Also, I think the turnstile at Magic Kingdom is bigger than it used to be. I am very hippy and had no trouble at all fitting through it this time, but had a tight squeeze last time we went.
Be prepared to have your items searched at the gates for security reasons.
Have a good time and tell Mickey Jana says HI!!
Jana