Screen resolution

Actually I thought that almost nobody use screen resolution less then 1024x768 in modern world. But according to latest VBWire survey - 40% of users use lower resolution, and these are mostly developers:
800 X 600: 24%
960 X 600: 16%
1024 X 768: 25%
1152 X 864: 16%
1280 X 720: 19%

Means that we have to write UI and web sites to be fitted into 800 X 600...