For 16:9 ratio, make your images 853p x 480 p @ 72ppi. That equals 1.17MB per image.
For 4:3 ratio, make your images 640p x 480 p @ 72ppi. That equals 900KB per image.
There is no point in making them higher resolution for DVD players.
Remember that the images will not look as good on a TV as on your computer, because DVD players simply are not capable of producing the same resolution. Blue-Ray will give you higher resolution, but that is another kettle of fish.