I still have my screen set to 800x600. I find that the text is too hard to read at a higher res and it's not like I'm that old
It really annoys me when a site is too wide for my screen. Some of them, like download.com, can't even be used at my screen res becuase the left side of the site is somehow missing.
Or they live in russia or something, and they just dont have that many new computers. On which 800x600+ resolutions are suported. You shouldn't totally forget about them