Hi Shannon, I started my daughter with Pigeon MagMag nipple cup when she was 3 months old. Now still this sippy cup and it works great. The teat is soft with a little horizontal opening to allow smooth flow of water.
Perhaps you can try feed your baby water using spoon first to get him to 'like' water. Then gradually introduce the nipple cup first. When your LO get used to the nipple cup, upgrade to the Sprout Cup, then to the Straw Cup. This is what my mom did to get my daughter to like water. Now she is happily sipping water from the sippy cup.
Hope this helps. [IMG=http://www.singaporemotherhood.com/forumboard/clipart/happy.gif]