I'll consider setting a fixed width, but the problem I have with that is that it alienates anyone with a *narrower* browser window. Figuring out exactly WHAT fixed width to use is very difficult.

How does having a site that fills the screen cause the user to have to do three clicks instead of two?

Also, just as a data point, Amazon.com fills 100% width on the screen as well, and they seem to be doing ok.