Why is my HDMI cable is making my screen smaller?

Before, I used the standard cables to hook my Xbox 360 to my Sony kdp-51ws655. Then I bought a 6 ft hdmi cable and used that. The picture quality looked a lot better, however, all the items on the screen were significantly smaller. I can read everything on the screen but i have to squint a little bit. Why is it making items on the screen smaller, and how I can I fix it?