K.O.
Hi J. - congrats! I just had my second in Nov - my oldest was only 14 months when the new baby was born. There are some good Karent Katz books and the one that she really related to was a book with the character Cailou - called Cailou's baby sister. It didn't really sink in with my daughter until my belly was growing and we let her touch it. We did explain that the new baby is coming and would practice - how we were going to pat the baby and be soft with the baby. The other thing we did which I loved, is that my daughter got a special build-a-bear stuffed animal the day before I went to the hospital, and that was her special bear that came with her to visit me at the hospital with grandma. Then once I came home, every day for about a week, she got to open a small gift that was to her from the baby. The opening of a gift and the new toys (actually birthday presents that we held back and re-wraped) - were a great new distraction and some great attention just for her.
Congrats and best of luck!