LG 29um57-p ultrawide monitor and Mac Pro 2008 resolution problems.

Just got a new (used) lg 29um57-p ultrawide monitor. The monitor looks like crap on my trusty 2008 Mac pro using dvi to hdmi cable (only choice on monitor is hdmi ports) Resolution is bad, fonts are alised and everything is stretched or too big or too small. Changing resolution just makes things worse. Looked through so many forums and cant find anyone with my situation with this monitor. I got this to have multiple window open at the same time for my internet radio station on one display. Just need the display to display as a clean and crisp.

Dvi to Dvi connection looks great on an old Dell widescreen monitor I had just sitting around. Guessing the problem has to be in the Dvi to Hdmi cable? Anyone have any ideas?

Thanks much

Taz

Other details that may help.

Graphics ATI Radeon HD 2600 XT 256 MB

OS X 10.7.5