1) forget the brand, there are only a handful f companies that manufacture the actual panels inside the TVs... so check the image quality in-store, and read reviews on the web, but don't pay extra for the brand.
2) make sure you understand the warranty. some companies won't replace the TV unless it has at least 5 dead (won't light up) or stuck (stays same colour) pixels.
3) make sure to get at least 3 HDMI inputs. i only have one on my lousy piece of shit TV, so i have to unplug the PC when i wanna use the playstation. if you get a digital TV signal (cable or satellite) then that's one port, one port for the bluray player or PS3, and you should keep one open (you never know what you need in the future, most people keep their sets for what, 5 to 10 years?)
4) the formats:
720p = 1280x720 pixels
1080i = 1920x540 pixels
1080p = 1920x1080 pixels
paying extra for proper 1080p is only worth it if you go bigger than 32", and then only if you sit quite close to the TV. of course, like i said above, you never know what you might need/want in the future, so going one size bigger and paying for 1080p might be worth it.
i only have a 26" 720p TV, but then again i use it only as a computer monitor and sit directly in front of it.
5) plasma TVs are cheaper and have nicer colours (they can produce true blacks, for example), but they usually have much lower resolutions than LCDs. they can also suffer from burn-in. i'd get one if it was only to watch movies in a home theater setting, but not for regular TV viewing.
