Janskeet said:
Could someone tell more the difference between letterbox and anamorphic again?

This is a very good visual comparison (pay special attention to the two photos a the bottom of the page):

http://www.thedigitalbits.com/articles/anamorphic/anamorphic185demo.html

The main point to remember is that letterboxed DVD images are essentially square(ish). They are made up of a widescreen movie image, sandwiched between two black bars that are PART of the image.

Anamorphic widescreen DVDs are rectangular in shape- like the movie image itself.