Well you could please everyone if you built your page correctly, simply to programmtically determine the browser resolution and dynamically build the page based on the resolution. However most dont want to take the time to do it - nor does it make sense to do this. But here is a couple of interesting studies on this.

http://www.utexas.edu/teamweb/reports/screen_resolution/index.php?log=May2005.log
http://www.thecounter.com/stats/2005/October/res.php

Both studies indicate that most users are at 1024x768 but there is a large enough minority still on 800x600 that you might want to take that into account.

I'd suspect most laptops up to the last generation (such as the IBM T41,42,43) tended toward 1024x768 since it is very comfortable for a laptop reader.

I keep my desktop at 1280x768 and my laptop at 1024x768 (its maximum). I find both comfortable based on the size of the screens I have.