Just some things to keep in mind when buying an LCD.
1. Response time. Yes lower is better, but make sure what numbers they are posting. Some times they post the black-white-black numbers and some times the gray-to-gray numbers. For gaming a good gray-to-gray time is better, but the black-white-black should not be ignored either.
2. Look at contrast ratio. The higher the better. This has to do with the contrast between the darkest dark and lightest light. A monitor with a higher contrast ratio will do better and producing blacks; LCDs have a hard time with black anyway, and sometimes black will appear somewhat purple in color.
3. Look at the viewing angle. The higher the better. LCDs lose image quality and color reproduction/clarity as you start changing your viewing angle from a dead on front view.
4. DVI input(s). Some higher end monitors will have dual DVI inputs, some will have a D-Sub and DVI, and some lower end units will only have a D-Sub. The little extra money for a DVI input is well worth it. Unlike a CRT, which is an analog device, an LCD is a digital device. Since the data in your computer is also digital, using an analog D-Sub input requires the digital data in your computer to be run through the video card's DAC to convert it to analog, then it must be converted back to digital at the monitor. This does result in lowered image quality, especially when viewing text.
5. Warranty. Make sure you know what the warranty is. I personally wouldn't touch a monitor that doesn't have a 3-year warranty that covers everything including the backlights; the warranty for the backlights can be different than the rest of the monitor.
6. Pixel policy. Since LCD panels cannot be tested for defects prior to the completion of the panel's manufacturing, most companies have a pixel policy that allows for a certain number of pixel/sub-pixel failures before the display will be warrantied. Full pixel failures will show up as a white dot (stuck on) or black dot (stuck off). Sub-pixel failures will appear as red, green, or blue dots.
7. Native resolution. When gaming on an LCD you need to consider the panel's native resolution. Since an LCD cannot span resolutions without loss of image quality, like a CRT can, playing at the native resolution is always preferrable. There are ways to work around this, by configuring the monitor to only use the pixels for the specified resolution. However, this will result in borders on the top/bottom, sides, or both. Aside from widescreen monitor resolutions, 19" LCDs use a native resolution of 1280x1024, and 20" LCDs are 1600x1200.