Is HD-TV the 100htz tv or is it some thing new? If its the 100htz which system (ie: crt lcd etc) do you recomend? and which make is the best affordable at the moment?

100Hz is actually the refresh rate of the picture on the screen while having nothing to do with the actual resolution or quality of the picture.

In Europe, most countries use the PAL standard, which has a frame rate of 25 frames per second interlaced. As the picture is interlaced, the TV draws all the odd lines on one scan and all the even lines on the next scan. This gives an effective refresh or flicker rate of 50 frames per second.

With larger TV sets, the flicker gets more noticeable and annoying, much like how 60Hz on a 17" or larger PC monitor can be irritating. To over come this, many TV manufacturers over come this by having some of their larger sets redraw the picture twice for every frame. This means the picture's effective refresh rate is now 100Hz and 'flicker free' to most people. The best way to see this is to visit an electrical store's TV section and you may notice that some of the large more expensive TV sets don't appear to flicker like the smaller sets. These 'flicker free' sets in fact use 100Hz refresh rate.

The only time a higher refresh rate is worth looking out for is if you plan on getting a CRT based TV. LCD & Plasma flat panel TVs and LCD & DLP rear/front projection TVs do not suffer from 'flicker' which means that a higher refresh rate offers no benefit.

Finally, don't confuse the refresh rate with HDTV. Standard definition TVs come in both 50Hz and 'flicker-free' 100Hz. The same goes with High Definition TVs. The key feature to look out for is "HDTV", 720p or 1080i. These three are all HDTV standards. For the best picture, look out for higher resolution. For example if you are interested in getting a HDTV projector, an XGA projector would offer superior quality to an SVGA projector.

For more information on deciding on HDTV or a large screen, see my thread - Choosing the Big Screen for the perfect home cinema or HDTV viewing

In summary, if you are looking for a low cost relatively small HDTV set (under 40"), then I would recommend going for a CRT set. For a large picture, a HDTV projector would be the best value to go for, assuming you get dark curtains for the room you are interested in setting it up.

thanks much appreciated