Make no mistake about it, we live in a visual world. The average web user takes 7 seconds to decide if they are staying on the website they opened or clicking off and going elsewhere. So you need to hire a company that can produce cutting edge design to attract your audience's attention.
But once you have them hooked, the writing must be able to deliver the message. If you are not communicating what is unique about your company - why customers should use your services and not your competition - the best graphics in the world aren't going to save you.