I prefer fixed over fluid ... but that is my personal opinion. design for 1024x800. Majority of the screens are at this resolution or better. 800x600 are a thing of the past, and used to be my maximum then. Remember to allow for the browser frame and scrollbar on the width. If your table or outside container div is set to around 980, you will still have room for gradient shading on the sides without getting the bottom scrollbar effect. On the vertical, this is hit and miss depending on how many toolbars a browser has, status bar enabled, etc. Shoot for a maximum of 600 for your 'above the fold'
I go for a 900 px width, sometimes a bit larger. Definitely fixed, you have absolute control over the site then.
I guess the width is/should be dictated by what type of background you are using. For instance, if you want an image of one of those cool looking anime characters appear to be peeking from behind your page, the width of the page may be smaller than 900. Depends on the background graphic. Tiled graphics, such as stripes, you would want just enough to show on each side. So widths between 900 and no more than 950 should be used to get the desired effect.
Well, well well. Wrong. Many, many people still use it, and it is the default resolution on Win 2000+ if you require proprietary graphic drivers. When designing a fixed site (I see absolutely no reason to though, people fail to realise print and web design are different things) you should subtract at least 32px from the width to get the width of your site. So if you were designing for 800*600, your width would be 768px. Its not much effort to do it in fluid though, in fact most of the times its easier, so long as tyou aren't doing the weird thing of designing your site in Photoshop then coding it - instead of the other way around :s
In regards to 800x600: Not too long ago, this argument was said in defense of 640x480 resolutions while wanting to design for 800x600. Should we still design for them as well? While 800x600 may be the default resolution for Win2K non-proprietary monitors, that has no bearing. After all, MSN Search is the default search engine for Internet Explorer. That is fodder for another topic though. One could argue that any website design that is unusable at 800x600 is not a good design. I guess the optimum term here is usable. One should also take into account the resolutions of hand-held devices such as PDA's and iPhones as well, and offer up alternate stylesheets for that media. If you look closely at well designed WordPress blogs, the majority of them are designed for fixed width screens of 1024. Kind of unusual, don't you think, considering that WP is XHMTL compliant, SE friendly, and all of that. Are WP blogs at 1024 still usable for smaller screens? I would argue yes. Most of the relevant content/navigation is on the left and the lesser, unimportant content is stuffed in the right sidebar. As long as your site is still navigational and readable, 1024 is a great design choice. (So what if they cannot see your blogroll, latest comments, etc. without scrolling) I suppose it may be easier. Is that vote for fluid? There are some fixed width sites that I read (like news) that have everything squeezed into a skinny column. First comes the headline, then the byline, abstract description, first one or two paragraphs, then bammmm, the 2/3 column width ad with all the text wrapping like a snake around it. In some cases, I wish all sites were fluid.