Hi Gail!
Children under three years of age do not require paid admission to the Walt Disney World theme parks, so that's one less thing to worry about on your vacation!
Also, I think you'll be happy to find that there are many rides and attractions that your two year can enjoy at the theme parks. There is a great Disney webpage
here that has information and pdfs including the very useful "Attraction Height Requirements". There, you see which attractions have height requirements and what they are for those rides....attractions not listed can be enjoyed by guests of any height.
I've found there is plenty to do on our visits to Walt Disney World with toddlers. A trip to Disney World with a two year old in tow is also an opportunity to see the magic through their eyes, and for me it always makes for the best memories on our family vacations!
Hope you have a magical vacation! Come back to the Moms Panel if you need any more help!