I could be wrong, but I think NTSC Television uses 400 lines that are 460 pixels across. These are interlaced so the pixels aren't exacly in a grid pattern like your monitor. I also don't believe the pixels are actually square. Now it's better to render your work at a higher resolution: I believe 640x480 is the magic number here. Like a photocopier, when you reduce the size of the image, you'll get a sharper image. Let me see if I can find a link to verify this or set me straight.