@Losttheplot: Ahhh - I think for the first time I know something you don't.
There is actually a 'HD Compatible' standard, with a very similar logo to the official 'HD Ready' one. It merely states that the set must take a HD picture. It doesn't have to have more than 576 lines of resolution.
From researching this (I last heard about it years ago) it appears it never actually got off the ground as it was thought it would 'confuse consumers'. Damn right it would have done! The only thing that comes close to backing me up is the great deceiver of Wikipedia
here