Creating commercial for 50" plasma?

1

i’m going to create a video using AFter Effects and Cinema 4D that will play on a 50" plasma. I want it to have those two black bars like when watching a widescreen format movie on your dvd player. What size do I create this in After Effects ? can I have it play full screen from a CD-R/DVD-R or is it better to have it play from quicktime 7 ? what size does the composition in AE need to be and exported as ? lots of questions ! my first time doing something like this.