What do I need to know about flat screen televisions to select the best one for me?

I don't know very much about flat screens. I don't want to spend a fortune, but I want to get a good one. So, what brands do you all recommend? What is the difference between plasma and lcd...or is there a difference? Does the little p after the number mean pixels or what and what is a good number? What about size...I want a fairly large one...I was sort of wanting something in the range of 32 to 50".