For the person who asked about switching to Eukanuba, that is also a no-no. You see both IAMs and Eukanuba are owned and produced by Proctor and Gamble, so it would be the same evil.
I go to a school that has a veterinary program, and Proctor & Gamble and Nestle (who owns Purina) pump a lot of money into these schools so that graduating vets (who really don't know any better) will recommend these products to their clients. For example, many vets will push the "veterinary diets" that are ailment specific. When in fact, in many instances, all a pet owner needs to do is increase the quality of their previous food and feed a super-premium brand. It truly is amazing what a SP food will do for a cat with urinary tract problems over a grocery-store, and even veterinary, brands.
I've helped a lot of people switch to SP Brands and the ones that seem to work the best for people are: Eagle Pack (probably one of the more cost-effective), Wellness (though some dogs had problems with their new formula), Innova, California Natural, Blue Buffalo, Natural Balance, Nature's Variety, Merrick (especially the canned diets), Solid Gold, and Azima (sp?)