North American HD TV signals are currently broadcast in 720p, Britain and some other countries use 1080i but as others pointed out they're effectively the same resolution. On sets smaller than 42" you'll have to be standing within a couple feet to see the difference in resolution between 720p and 1080p, at a normal viewing distance it's physically impossible for the human eye see the difference between the 2. Even on a 50" set you cannot see the difference between 720p and 1080p at 10', the effect beyond that distance is psychosomatic... you "see" more a cleaner picture because your mind "knows" that 1080p is better.
1080p is only really important on 55"+ sets or if you're sitting REALLY close to the tv. For the size TV you're talking about buying I'd ignore the 720p vs 1080p spec and concentrate on which set has the better feature set that you're likely to use, better overall build quality and rating, better warranty, etc. If all other specs are equal, buy the 720p model because it'll be cheaper... no point in paying for marketing hype that you can't use anyways.
