Will the less resolution not make a difference?
Have you ever seen a good 720p signal displayed on a 1024 x 768 panel and felt that you could not see enough detail? While viewing the whole image, your eyes cannot even resolve that many pixels, so no, it really makes no difference.
If you are going to sit very very close to a big screen, then sure, you don't want the pixels to be large enough that you can actually see the shape of the pixels, so on 60" screens, sure get 1920 x 1080 or better. On 42" at 2.5 meters or more, it really does not matter. It is really more about the size of the pixels than the number of pixels.
Native resolution is the only factor/spec that is easily quantifiable. A panel's resolution can be quoted exactly, they don't say more or less 2000 x 1000 ... it is exactly 1920 x 1080 etc.
The other picture quality factors are also measurable, but much harder to check whether the manufacturer is making bogus claims. Black levels, colour gamut, motion processing etc. All of those are however much much more important to picture quality than the native resolution (once you go over 720p), but most people will still base their decision solely on 1080p vs 720p
Nobody is his right mind will claim that a 16MP point-and-shoot camera is gonna take better pictures than a 12MP Canon 5D, but when it comes to TV's, hell, then that is all that matters. Incidentally, with photography it is also about the size of the pixels and not the count ... it is absolutely fine to print postcard sized photos from a 6MP source ... you only need uber-many pixels if you're going to print very large, because you still don't want to be able to distinguish pixels when inspecting any smaller part of the big printout.
fanatic, I would recommend full HD plasma for sure. 
Not letting you down team!