Simply being informed about an employer does not guarantee a successful interview unless you use that information effectively. Knowledge of products and opportunities is only helpful if you know how to tactfully weave that knowledge into the interview. Spouting out facts or prefacing a question with a lot of memorized details will not convince the employer of your interest and/or knowledge.
During the interview, most employers will ask some variation of, "Why do you want to work for our organization?" or "What are your long-range career goals?" Relating your skills to those in the literature which seem to be needed for a position, or valued by the organization in general, can be an effective way to show that you've done your homework. Remember to bring in transferable skills like communications, writing, sales, or computer knowledge. Before the interview, brainstorm how you can help the employer be competitive in specified markets found through your research.
Another way to incorporate information is through the questions that you ask the employer, usually towards the end of the interview. Request information only on topics you really want to know more about, and avoid being too detailed or projecting a "know-it-all" attitude. Ask questions that encourage the employer to expand on information from the literature.