I love seeing how wrong people were back in 'the old days', ie. the 90's. So you could imagine how fun it was for me when I found this ancient website telling people all about screens. I find it hilarious that there was a time when a 1600x1200 resolution was "Terrible" on a 14-inch monitor. I mean, a DPI of 142 is nothing compared to say, the Retina display on the iPhone 4S, or the 720p HD screens on the upcoming Galaxy Nexus and HTC Rezound, but it's pretty good for a (albeit tiny) monitor. It's certainly better than the hideously unacceptable 640x480, which the site deems 'best', with it's measly DPI of 57, which is odd, because the site then states that Mac renders text assuming 72 DPI, whilst Windows assumes 96, so the best would be 1024x768, because the site is optimised for it and it's in between both those sizes. It is referring to the text size. In the 90's, computers could not scale text, and didn't actually know their monitor's DPI.
The bottom right cell is accurate, though - that's about standard in monitors today. Although we use 16:9 or 16:10 instead of 4:3, but that's about the same DPI and a similar size. I imagine, though, that when this was written (based on the Mac OS screenshot, I place it as late 1999) a 21-inch monitor would have been outrageously expensive and near unheard-of.
I also found this quote: "Larger monitors must contain smaller pixels in order to maintain the same resolution". That's simply wrong, because, if he is talking about the amount of pixels (the actual resolution), larger screens actually need BIGGER pixels than smaller ones to maintain the resolution, because there's more space to put the same amount of pixels in, but he's using the term 'resolution' wrongly, referring to the DPI. For the DPI to remain constant the pixels need to be the same size. That's what that means. If they're smaller, you have a higher DPI. If they're bigger, you have a lower DPI. You will not keep the DPI the same by shrinking the pixels, and if you're talking about pixel size and DPI, screen size is irrelevant.
Furthermore, this person seems to be of the belief that you should change your computer's resolution. Under no circumstances should anyone EVER change the resolution of their computer from their screen's native resolution. You lose sharpness, all the elements are too big/small, the computer can't optimise the display for your screen, and it just generally looks horrid.
OK, rant over, I don't want to be annoyed at 90's people. I'm sure they were just ignorant/primitive. I'm also sure that the people of 5-10 years in the future will look back at us and scoff at things just like this - Flash, perhaps, or RAM. Or displays that aren't transparent. Or lack of hover technology. "McFly, you bojo!", they'll say, "Those boards don't work on water!"
"Unless you've got POWAH!"