There's always the discussion about whether or not designing for 800x600 is still vaild or not. The argument against it is that most computers sold these days are at least 1024x768, However, that doesn't necessarily mean that the surfer browses full screen.
So I'm running some tests on a small site using javascript to grab the actual "window" width etc. There's some issues with it that I need to review, but here's some stats to date.
What I've done is arbitrarily split the width into greater than 900 pixels and less than 900 pixels to simplify things. Perhaps I should have picked a different value.
5460 hits logged...
Screen: 1024 x 768 : 2803 (51.34%)
window width > 900 : 1822 (65.00%)
window width < 900 : 981 (35.00%)
Screen: 1280 x 1024 : 772 (14.14%)
window width > 900 : 593 (76.81%)
window width < 900 : 179 (23.19%)
Screen: 800 x 600 : 611 (11.19%)
window width < 900 : 606 (99.18%)
window width > 900 : 5 (0.82%)
You'll notice there's something "odd" here given 5 of the hits registered > 900 yet the screen reported it was only 800x600.. I'll have to investigate this.
Screen: 1280 x 800 : 488 (8.94%)
window width > 900 : 329 (67.42%)
window width < 900 : 159 (32.58%)
Screen: 1152 x 864 : 246 (4.51%)
window width > 900 : 182 (73.98%)
window width < 900 : 64 (26.02%)
I didn't calc any window info for the ones below:
Screen: 1440 x 900 : 144 (2.64%)
Screen: 1280 x 960 : 87 (1.59%)
Screen: 1680 x 1050 : 70 (1.28%)
Screen: 1280 x 768 : 62 (1.14%)
Screen: 1400 x 1050 : 46 (0.84%)
Screen: 1600 x 1200 : 22 (0.40%)
Screen: 1920 x 1200 : 20 (0.37%)
Out of all 5460 hits (and this is probably the most pertinent):
window width > 900 : 3333 (61.04%)
window width < 900 : 2127 (38.96%)
So it would appear that designing a site for 1024, it going to iritate 38%+ of the surfers since they'll have to readjust their browser in order to view it properly.