What you're looking for is a low Video Response Time. This is the time it takes for the liquid crystal to turn to draw a new image. With a high response time, you get ghosting in high FPS applications, because the LCD won't update quickly enough to display the information the video card is sending to it.
16ms is about the fastest Video Response I have seen, but it can range up to 50ms. At 16ms you won't really see a difference between a CRT and an LCD. 25ms is descent though.
A high Contrast ratio and NIT can make a big difference in image quality, but if the Video Response is crappy, high FPS game playing is unbearable.
