For the widescreen question:
When you start games, they are usually made for regular screen ratios, so if you rigth click a desktop shortcut icon (say BF2), click properties, and you look at the command line box, you can see the path to where the game is located on your computer. For my widescreen, I always have to add -szx 1920 -szy 1200, because its a 1920.1200 resolution monitor, so you would change it for yours. Each games has different 'codes' or commands, instead of szx or szy, it could be height and width, just look at google it is easy to find. If your graphics card can handle it (yes, you need a decent one), you can make the games look pretty sweet.
For the TV question:
If you don't have a HDTV, the resolution will suck. Thats it. The cheapest monitor will kill the best non-HD tv any day in terms of how it looks.
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