LCD TV Calibration and picture Quality

I bought a new Sansung ln46B650 LCD TV and I hope to use it as the display for my HTPC.
On its own the TV channels are fuzzy at best and a disappointment so far. I  tried calibration settings that have been published on the Internet for my model, but with no big improvement. I woul like to solve this problem before connecting it to my Media Center computer. Also I would like to understand what will matter most when connected to the coputer.. the display settings or the video card settings. How do I get the best result so that I can get the best picture quality. I am experimenting with envida gefore 9500gt  and a ATI Radeon HD 4650 card. I am trying to determine what works best. But so far the video card doesn't seem to improve the TV viewing quality.