You may have your heart set on a new TV, but I would suggest investing a bit in accoustical room treatments. That would help you get the most out of your current and future equipment.
If you check out
www.auralex.com , they will give you a free basic room assessment if you fill out the form. It costs nothing to get the assessment done, and once you do it you aren't obligated to buy anything. It's worth considering though.