Good info here:
http://reviews.cnet.com/4520-6449_7-6734875-1.htmlCopy and Paste from another source.
Console Info:
The main trait of HDTV is its super-high resolution: at least 1080 lines from top to bottom (aka 1080p). The question is, what are the resolutions of the game consoles out there?
Sony Playstation 3: up to 1080p
Microsoft Xbox 360: 720p to 1080p
Nintendo Wii: 480p
Burn-In
What it is: a visible mark is "burned" into a TV screen when an image has been left on the set for prolonged periods. It could be that heads-up display (HUD) containing your life bar and other game stats that never disappears from the screen for most games. Only plasma TVs (and CRTs) are susceptible to screen burn-in.
How to fix it: allow your HDTV to "break in" for the first 100 hours or so. That means you shouldn't put too much strain on your plasma TV by leaving static images on during that time. Other things you can do: tweak contrast and brightness settings and make sure you buy a set with anti-burn-in features.
Lag
What it is: because not all games are in full-HD (1080p) but only have 480p or 720p, the images in the game have to be "processed" to be rendered properly on an HDTV set. The processing time is more or less the lag itself.
How to fix it: If you're playing highly time-sensitive games, this will be a big issue and you might need to purchase equipment to eliminate the lag. HDTV sets today also claim that their "game mode" feature reduces or even removes the lag---be sure to check it out first. If don't care for a delay of about 6 frames or 1/10th of a second (worst case), then you need not worry.