Do bear in mind that the nes games will be in 256 x 240 (or an upscaled version of).
http://nintendo.wikia.com/wiki/Nintendo_Entertainment_System
So I guess if you forced a widescreen view the aspect ratio would look odd unless you have black bars at the side.
SNES resolution:
http://www.gamefaqs.com/snes/916396-super-nintendo/reviews/review-22549
