Smart Analytical Geek Required

I am agonizing over a wide screen TV for my bedroom and I lack the brainpower for the following question: If I play the letterbox side of a DVD through a 32" widescreen TV, does it automatically fill the entire screen? If so, how big would a 4:3 standard TV have to be to project the same size image, excluding the black bars on the screen? Thank you very much.
William- I hope I am none of the above, but I can tell you some of what I know: a letterbox DVD typically was not shot in exactly 16:9, so will not fill entire frame unless it is listed as anamorphic (I think). The 16:9 format is a compromise between typical cinematic and standard TV format. As far as the screen size, I will tell you that my 30" Loewe widescreen, when used in the 4:3 mode has a slightly smaller image size than my 26" Panasonic. My guess it would have to be considerably larger than a 36" 4:3.
I may be wrong, but I don't think so. On a 16x9 widescreen, letterboxed movies shot in a 1:85:1 aspect ratio WILL fill the entire screen while those shot in 2:35:1 WILL NOT. On 2:35:1 movies, even with a widescreen you will still have the black bands across the top and bottom of the screen. My understanding of anamorphic is that on a 4x3 set an anamorphic transfer will utilize the TV's horizontal resolution lines to create the "black bars" (which is bad because you are then able to use less horizontal lines to recreate the picture in the movie), while on a widescreen all the the TV's horizontal lines are used to create the movie picture NOT the black bars. Anamporphic transfers are thus obviously better viewed on a 16 x 9 set. I can't explain how this works, so don't ask me! I would also think that you would need at least a 36" standard set to recreate the size of image from a 30" widescreen, but that's just a guess.