A 19" LCD will likely be 1440x900 resolution in widescreen, or 1280x1024 in standard resolution. As said, widescreen lets you see more which COULD be an advantage in games, especially online. However, I find that the less then 1024 up and down really isn't cool. This is why I personally am trying to hold out and buy a 1680x1050 20.1" widescreener. Even more real estate, and higher resolution.
For the 19" range, I'd go with which has either a better name, better reviews, higher contrast, etc.
Post up links to what you are looking at.