Have you gone into the menu for the display and calibrated it. Additionally is the display the same size as the one you had prior or did you go with a larger display. Sometimes the crispness is gained in going with the native resolution that your display should be at vs the display resolution of a prior monitor.
Regarding HDMI cables, I have heard that poor quality cables can have effects like this and a newer HDMI cable of better quality might resolve the issue. Only problem I have ever had with a HDMI cable though was one that oddly was directional specific to where it was labelled at one end for TV and other end for Device and if its connected backwards it wouldn't work at all. I got this cable in a box of other cables when someone sold me a computer 2 years ago and gave it to my daughter for her to use with her PS3 since I use VGA and DVI cables for my computers.
I went from an older display though to a newer wide screen and it seemed blurry and by increasing my resolution to that of what the display manufacturer recommended everything got crisp for picture.
