I understand the first HDTV purchase can be a little overwhelming. Some things to consider... Plasmas are beautiful and I think they have the best picture (and are less expensive in general). But if you're going to hook up a PC to it and you leave static images on the screen, that could become a problem for you. I had one for a year and started seeing image retention from watching too much ESPN (static scoreboards and the ticker). Otherwise, great TVs if you're varying your viewing content. LCD images are nice, but not quite as natural as plasmas and the viewing angles aren't quite as good. But still a great TV. LEDs typically have better color and black levels than traditional LCDs, but are also more expensive.
My preference is 120hz over 60hz. I can see the difference in the motion. Many people cannot and will swear that those of us who prefer 120hz are crazy. I had two LCDs of the same brand and had to take the 60hz back because the motion was bothering me. The 120hz version fixed that issue for me. Watch them at the store to see if you can see the difference. If not, then try the 60hz and save some bucks.
720p vs. 1080p, well, in the sizes you're considering, you're on the border of whether you would really need 1080p, but I would recommend it in this case since you mentioned you'd be sitting close to the TV. Also, it will make a difference using Bluray or HD gaming. I agree with the previous poster about Sonys going downhill in recent years. I have a Samsung LCD after trading in my plasma and am very pleased with it. Their customer service when dealing with my IR issues on my old plasma was tremendous too. Everyone will have differing opinions about types of TVs and brands.
Keep in mind that Best Buy has a 30 day return policy (it may be more now with their new program, but I haven't looked into it). Anyway, you can return a TV for any reason and try a different TV if you're not satisfied. So that takes some of the pressure off. Best of luck with your search.
