hsrob on 13 April 2009
Several people have quoted as fact, the various TV sizes at which the difference between 720p and 1080p is noticeable, you must also consider, as alluded to by several people, viewing distance.
If you sit 1m from your screen you are going to see a difference even at small screen sizes. If you sit 4-5m you may not notice a difference unless you have a huge TV.
Sure this may vary from person to person according to how good your eyes are but assuming normal eyesight, the distances and TV sizes at which the differences are noticeable are determined by physics and what the human eye is capable of resolving.
So to answer your question, have a look here.
http://www.engadgethd.com/2006/12/09/1080p-charted-viewing-distance-to-screen-size/
