what does HD ready actually mean with regard to HD standards?

The standards for current broadcast are on 540 scanning lines, which means that the picture is broken into 540 rows, and all 540 are refreshed according to the Hertz rating of the television (usually 50-100) which gives a moving picture.

In HDTV there are either 1080 or 740 lines, which are refreshed at the Hertz rate. The practical upshot of this is that the pixellation of the picture is condensed. The effect is rather like the fineness of the grain on a photographic negative- the finer the grain the clearer the picture.

Beware of HD emulation which is not true HD and doesn't always work the way it should. Lots of televisions only work in the lower register of HD too, particularly the cheaper ones.

Very few broadcasters are actually using HD broadcasting and you will need extra equipment to receive it. This will not be cheap. Because of the different technology it is not possible to convert existing sets to high definition, and the cost is a major setback to the take-up of HDTV. Another consideration is whether you can receive it terrestrially. If you have Sky there isn't a problem receiving it, but again you will need Sky HD equipment and a new LMB will have to be fitted to your dish, or a new integrated dish installed. Sky can be reticent about the prices for this but they do some packages and it's best to call them and find out how much they're willing to do it for. Again you will need a TV set that can work in HD and none of the cathode rays as far as I know are capable so your choice is LCD and Plasma- EXPENSIVE.