You'll have a good time. Here are a few tips I've learned after visiting Disney numerous times with two children; the first time my daughter was 3.

Go to the parks early in the morning. I know it sounds like a drag on vacation and I'm not a morning person AT ALL, but if you find out what time the parks open and you make the effort to be there for the 8am or so opening, you will see a lot, ride many of the rides and have a great time before the park gets unbelievably crowded and extremely hot. At Magic Kingdom, go straight to the area with the Pooh, Peter Pan, Snow White etc. rides. You can see them all during the first 90 minutes. Use the fastpass system wherever there is a wait of 45 minutes or more. Believe me, you want to be leaving the parks by 2pm when all the other sunburned parents are desperately trying to soothe their screaming children!

Also, bring a backpack and put some snacks in it. We found that lines are tolerated by small children much better when you have crackers, goldfish, pretzels, Nilla wafers, etc. to hand out. Lines become snack-time. Just make sure you have water bottles in there too. Lollipops work well because they take just the right amount of time to eat!

And, take advantage of the fact that you can leave the parks at 1 or 2 pm and go home for naptime. When they wake up at 4 or 4:30, you can make your way back to the park by 6pm, do a few more attractions, eat and catch a parade.

Finally, make reservations in the parks for dinners if you think you'll want to eat. Don't get stuck trying to figure out where to eat with a hungry toddler. And, consider buying a book like "The UnOfficial Guide to Disney". It has great reviews of what attractions are good for small children, and which ones will absolutely ruin your entire day! Money well spent!

Have fun and enjoy the wonder of Disney as it is seen through your child's eyes!