I have the same type of service that TXHRGuy has, but I use Labor Law Center, Inc. I would recommend a service like this, as you don't have to worry about remembering to order a new poster everytime the law changes. Last year alone I think I got 4 different sets of posters between federal and state changes.
To answer your specific question about the poster, I would call one of the services like these and ask them what the requirements are for your state and see what they tell you. Or better yet, call both of them and see if you get the same answer.