My November stats so far:
Screen Resolutions Unique Visitors
1024x768 166153 55.64%
800x600 77048 25.80%
1280x1024 28152 9.42%
1152x864 14743 4.93%
Other 6004 2.01%
1600x1200 3834 1.28%
640x480 2647 0.88%
I say you MUST code for 800 x 600!
I also say if you use 640 x 480 you should be fucking shot.
