Get widescreen. Fullscreen, aka "pan & scan," has the sides of the movie cropped out by the studios in order to fit into a 4:3 aspect ratio.
Widescreen, on the other hand, is true to the source material and can range anywhere from 1.77:1 (16:9) to 2.35:1. With the Touch resolution at 1.5:1, you'll see only very slim black bars, usu. on the left & right, when you convert a DVD to it. And, it's the whole picture - not something arbitrarily trimmed to look different before you even get it!
Besides, won't you watch the DVDs on a TV at some point? You'd want widescreen then anyway.