I am getting to the stage where I am going to upgrade my ancient TV for a flat screen to be HD ready when it happens.

I am not too much into 3D because besides giving me a headache and making my eyes water, I think it is a passing fad.

What is the difference between LCD and LED and Plasma?

remember I am a 'Technodatyl' so easy English words will be appreciated.

I have an inkling that they are all Plasma and are lit by LED or other systems.
I surmise that LCD stands for (Liquid Crystal Display?) is that different to plasma?

Then most importantly, list in sequence which system is likely to be cheapest, last the longest and use the least electricity? so that the little old man I am can make an informed choice.