'HD Ready' means that the set has a HDCP compliant HDMI input, and can display at least 720 lines of not less than 1024 horizontal samples, - that's it! So one of these sets is 'ready' to display an HD digital stream from any compliant external source, e.g. Blu-ray, (HD-DVD for those into obsolescence), HD gaming platforms, (PS3, newer X-Box), Media Streamers, certain HD camcorders and of course external TV Receivers (so called 'set-top boxes').
To be called a 'TV' the set must have a tuner, but there's nothing in the spec that says it needs to be digital, let alone HD, so 'HD Ready' has nothing to do with the reception of HD broadcasts. Just look at the list on this web page:
High Definition TV Displays | Search Results
Whereas the manufacturers of all devices that can receive and decode HD broadcasts (Terrestrial/satellite or cable) are entitled to affix an 'HD TV' logo, which I assume will start appearing on new sets when they are released in a few months. The logo already appears on set-top boxes that have this capability.
here are the rules for that logo:
http://www.digitaleurope.org/web/news/telecharger.php?iddoc=585
Remember, all set-top boxes are effectively the same, (Sky HD, Freesat HD and Freeview HD) as far as an HD Ready set is concerned. So the only con is where dealers are implying that the set is 'HD TV' when it is only 'HD Ready' and buyers haven't asked the right question,
runas