Using older Cinema HD Display with newer Mac Mini

Hi. I've just purchased a new Mac Mini running Mountain Lion. My display is an older 30-inch Apple Cinema HD Display. I hooked it up using the cable that came with the new Mini and it works but everything displayed is in what can only be described as "Grandma Mode" meaning everything is large, blurry, and bitmappy. My Apple Cinema HD Display has a Firewire cable that isn't compatible with the port on the back of my new Mini. Could this be the problem with the oversized display? I've tried setting up the resolution in my Display Settings but it makes no difference. Is this a software issue or is it the Firewire or something entirely different?

PLEASE HELP! I'm a graphic designer and I have deadlines to meet. I cannot work in Grandma Mode! Thanks for your time.