There are a number of arguments for choosing to buy an HD TV and all of them make sense in one way or another. With the prices of HD Ready TV's falling, the availability of HD broadcasts increasing and the incredible picture quality of HD, there's never been a better time to upgrade to that HD LCD TV. However, there are really only 2 main reasons you need to upgrade:
The quality difference between a HD picture and conventional analogue TV is immediately evident. You can see details that you've never seen before on a standard television. Like the advent of color televisions, once you watch HD there really is no going back.
Most countries will be switching all analog TV signals over to a digital one at some point, for example, in the US the current switch date is June 2009. This means that you simply must have a digital TV to watch television.