Arctic wrote
For fixed width, use either 720px, 840px, or 960px. The last width, 960px, is the largest you should go to at this time (1024x768 is more common than 800x600).
Fluid layouts can have issues with line-lengths. Most web developers aren't using fluid layouts anymore (line-lengths get too long), it's usually fixed or elastic (width based on font size to preserve line-lengths).
I agree. I always create sites at 1024x768. Just make sure you develop on that resolution as well or you can end up with some messed up stuff. test with different browsers and resolutions to make sure it looks good in every environment.