Although high definition TVs are pretty well the latest thing, they're not all that new. In fact, the term 'HD ready' has been officially used in Europe since 2005 to identify equipment capable of processing and displaying high definition signals.

The outcome is that the market is well established with lots of choice, meaning you've got a good chance of finding cheap HD TV that meets your needs. It is possible to buy a genuine HDTV for under £200 or $300, although at this price you'll generally get a relatively small screen size of 22 or 24 inches. Increasing the size and adding in features can push the price up significantly, so you need to know what you're looking for.

Buying a new HDTV might seem easy - decide on a screen size, choose a model that's cheap and gives a good picture, then pay for it. But it's not as simple as that and you need to take lots of other things into consideration.

First of all, ensure it's a genuine HDTV, which means it must have a minimum 720 lines and preferably 1080. As regards picture quality, TVs in showrooms invariably have the highest picture settings to give the best impression. The showrooms are also usually well-lit, so try to get the TV's controls set to equal levels in terms of brightness, contrast and colour as well as reducing the amount of light shining on the screen. That's more likely to replicate how it will be in your home.

Most new TVs have an extensive number of input and output ports for connecting external devices. These can be confusing and many people steer clear. But it is important to ensure there's at least one HDMI input that supports 1080p and HDCP. This ensures you can plug in a Blu-Ray or HD-DVD player, which ensures the best quality input and future proofs your investment for some time.

If you can, play a familiar DVD on the selected TV. Periods of fast action will test the set's processing speed, with shaky movement and picture break-up suggesting poor performance. Many sets have preset picture modes, such as Movie and Sport, so try them out to see the effect. Also, don't forget to check the sound. HDTV can produce surround sound and you may need extra speakers to take advantage of this.

Should you be planning to use the TV for games, ensure you can connect your games console and everything will work. Take your console along and try it out to be sure. Most games will look better on a HDTV.

As with many products, buying from a website will generally give you the best chance of getting a cheap deal. However, you really need to see your chosen TV in action before you do this. Check the online vendor's returns policy and don't forget to factor any shipping fee into the cost. This might reduce the attraction of buying online.