LED is a bit of a marketing gimmick.
Actual panel wise they are basically the same as one advertised as a LCD, the only difference is how they are backlit.
Anything advertised as LCD will generally have a CFL light source behind it (usually a couple of horizontal tubes) and a diffuser to make it a single uniform backlight.
Most advertised as LED will actually be edge-lit LED , this means the the lighting is done by LED's that are arranged around the edge of the screen which allows the screen to be thinner.
The best LED ones will be full-array, which means there is an array of LED's behind the screen, this means that individual parts of the screen can be lightened or darkened, and some of them are actually RGB LEDs so that it can change the colour of the backlight. This is the best for contrast and quality.
This is a decent description with some diagrams if you're interested.
The long and short of it is quality wise:
Full Array LED > Edge Lit LED > Backlit LCD
If it's only going to be used for Xbox gaming then there's no real need to go for a higher res monitor over a TV based one.
I personally use a Samsung Syncmaster TV for my PC monitor. It has pretty much every input under the sun, HDMI, DVI, VGA, Digital TV tuner, I originally bought it as a bedroom TV and had my Xbox running through it until I accidently threw a cup of coffee over my normal monitor. I originally planned to only use it as a temporary replacement, but it's now been there for about a year as it performs reasonably decently as a monitor as long as you don't want a higher res than 1920*1024. (which does me fine).
