800 by 600 pixels, A very common screen size (extract from bpresent's webmaster tutorial)
This page shows a representation of what is arguably the most common screen width and depth in use today [12-Jun-2004]. Namely 800 by 600.
Even though there are many users with much greater widths available to them - especially corporate users and developers - if you are in small business and are targeting home users, you would probably be best to design with 800 by 600 as the maximum (ar at least the ideal).
The problem with this approach is that, on larger screens, your web pages can look absurdly small, especially if it is left justified.
There are ways to design around this, without using expensive add-on products. It's not a bad idea to take a look at the biggest and best (eg. Google and Yahoo Mail) and imitate them. Both their opening pages are simply center-justifyied with white space on either side.
The approach we eventually settled on was to design for 800 by 600 but allow the page to grow (to a limit) for larger resolutions.
Most of the pages on the bpresent.net site (this site) will shrink width-ways down to fit on about 500 pixels and will expand up to about 810. The notable excpetions are on this tutorial, which expand up to about 1000 with the menu on the right hand side.
Note that if your font size is set to greater than the default dpi then it's likely this page is deeper than 600 pixels.
600
minus
70
 
(for
the
tool
bars
-
hard
to
predict!)
800 minus 25     (for the borders and side scroll bar - in IE)