Those are the pretty obvious facts. But Dell seems to have taken the facts one step further, as can be seen on this learn more webpage "How Screen Sizes are Measured" at Dell’s website.

I first spotted this page about a year ago, and thought it was just a mistake on Dell’s part and someone probably would point out sooner then later. Who ever said that the CRT screen measurement includes the plastic case? We know that CRT’s stated screen sizes are measured as the diagonal size of the CRT tube, and because of the borders, the actual viewable screen sizes are about one to two inches smaller then stated. But I never heard of this kind of measurement by including the plastic casing.

In my opinion, this is clearly a false advertisement and Dell is certainly aware of.