LCD vs Plasma
The first decision is whether to get a Plasma or LCD TV.  Both technologies have their own drawbacks but on the whole LCD TVs tends to perform better. The problem with LCD is black levels and slightly blurred motion. However, modern LCD TVs have greatly improved on both of these issues. Plasma TVs have excellent black levels and can generally handle motion well but suffers from image retention, an effect similar to burn-in. While games tend to have a lot of motion, there is always a static element on the screen (health, ammo etc) which the phosphor layer remembers long after the console is switched off. The images will fade over time and some televisions even come with options to remove them faster but it is a problem nonetheless.

1080p vs 720p
The last few years have seen the rise of 1080p (Full HD) TVs to usher in the next era of HD video. Both the Xbox 360 and Playstation 3 offer 1080p game play, but not consistently. Most PS3 games aren’t actually 1080p, so if you have a PS3, a 720p TV will be fine. Xbox 360 doesn’t come with HDMI and most televisions don’t support 1080p via Component so a 720p TV is also fine for Xbox gamers. You should consider a 1080p TV if you want to take full advantage of Blu-Ray movies or if you have the Xbox 360 Elite which comes standard with a HDMI connection. There are some PS3 games that support 1080p but if you are on a budget, a 720p TV will do the job perfectly, even when watching Blu-Ray.

100Hz, contrast and response time
100Hz technology has been introduced to some televisions (with mixed success) to smooth out motion. It comes at a premium but, if done well, it can enhance gaming, especially on LCD televisions. gadget zone recommends Sony’s Bravia range for an example of 100Hz (called Motionflow by Sony) done well.

Contrast is measured as a contrast ratio which is the number of steps the panel can take between white and black.