Absolute positioning is evil.
1.) If I have a low screen res, even if I am a minority (which I don't), then I have to scroll both horizonally and vertically, and I don't come back.
2.) If I do have your magic number (which I don't), then I have to be surfing with the window maximized to enjoy the content of your site. If I want to have 3 wondows open and activly watching them (like my Tv card output or an IM program along one of the edges) them I end up with horizontal and vertial scroll, and I don't come back.
3.) If I have a screen resolution a lot higher than your magic number (mine is 2048x768) then there is a lot of "dead space" that isn't being used. I become annoyed, and possibly don't come back to the site.
Keep in mind the other "silver" that might be gobbling desktop realty, like the menu and task bar (on any of the four sides), a "slim" mp3 player program, an IM program latched to one of the two sides (don't thing any go hoizontal), news tickers (typcially horizontal) and any other oddity. Then again, if a sites sizes annoys me I just override it's CSS (gotta love the CSS extention for fire-fox).
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