Earth's Best Rice Cereal was the only rice cereal we could find at any of our local stores that doesn't contain soy. It's available in all our local grocery stores - Shaw's, Stop 'n Shop, Whole Foods, and Sudbury Farms, as well as Target. You can also buy their products online:
http://www.earthsbest.com/products/product/291.php
They have a whole line of products that we have used, however, with Emily now having issues with protein, we're sticking with the fruits and vegetables as well as the rice cereal only.
Emily wasn't a fan of rice cereal at the beginning. We took the suggestion from our pediatrician to add in a little veg or fruit to give it some flavor and she's been eating it ever since. We tried the other cereals, but they bothered her stomach so it was suggested we stick to rice only as that doesn't seem to bother her.
Emily rating: 8/10 (only because she doesn't like it without something mixed in)