Easier for You
Why create two websites, splitting your traffic and time? Have one website for both the PC and mobile user. That way you will only have one site to maintain, reducing your administrative costs.
Better for Your Visitors
A responsive design will both improve your search engine optimization and help you deliver your message to users on the go. Remember, users are more likely to take action if they have easy access and a good experience. A responsive design will deliver a good experience no matter what device your visitors are using.