Stats tell us a myriad of things, some even useful and we're accustomed to using them in our marketing and selling processes. Frequently abused and made to say what WE want, but here I am merely considering them in ways that influence site design ... and, I believe, letting numbers speak for themselves.
Before finalising my own choices for recent (and always in progress) re-design at http://www.tucats-design.com I had a look at my stats and at various global statistical information online.
For this exercise, I took a glance at overall picture via third-party service I use from http://www.thecounter.com -- all my pages have their invisible option installed. Raw log stats will tell you a whole lot more, but this serves purpose.
OK, I'm lazy and I like getting their weekly report by email.
The information (percentages) for my site are those used for analysis below. The global stats I consulted didn't show any fundamental differences from these findings, i.e. they should apply to you too unless your site only caters to some specific group that is far and away from average.
Unknown (2%) 640x480 (9%) 800x600 (61%) 1024x768 (23%) 1152x864 (1%) 1280x1024 (1%) 1600x1200 (0%)
It wasn't that long ago that there was a case for making sites at a fixed 600 pixel width to fit 640 x 480 resolution. For single-product sales letters, I think there is still a case. It looks better than having lines stretch across too wide a portion of screen, even if visitor does have 1024 x 768.
If you have more content to link to, you need space for menus and stuff. Is it safe to use a bit more screen real estate? I take my lead from Boogie Jack - http://boogiejack.com -- in that when a group drops below 10%, then it is safe to stop labouring too hard to make things absolutely and perfectly compatible.
The percentages above too are taken from cumulative data -- that is those built over time. What they don't show is that 9% using 640 x 480 could have visited months ago. I certainly know that percentage has been dropping as time has passed.
So, to fit in with now most common 800 x 600 resolution, I am using a fixed width of 750 pixels for tables that form basis for my design. Now it's true that you could just design in 100% widths so that it will adapt to everything, but it is just so much harder to do, especially if you want to use tables with multiple columns. The chances are high that you'll put some image somewhere which mucks it up. Been there!
As you can see, 1024 x 768 has now jumped up into second place (I use that resolution myself) at a pretty meaningful 23%. Yet I see sites every day that look absolutely awful at that resolution because they were designed for smaller sizes, but using 100% width tables. You really need to consider this group now.
However, it is easy to test and easy to change your resolution. For vast majority of you using Windows 98. Simply Right click on any blank portion of your desktop and select "Properties" from popup menu. From there, select Settings tab.
You'll see a slider control in bottom-right of that window, which will probably go from 640 x 480 to 800 x 600 and 1024 x 768 on right. Choose any option and you'll have 15 seconds to "test" after which machine will restore automatically to your previous settings, unless you tell it otherwise.