Folks, for what seems like ever, we web designers have made our pages just over 700 pixels wide. Why? Because the vast majority of people had small screens with the resolution set to 800*600 (that's 800 pixels wide, and 600 pixels tall). Take away scroll bars, and browser window panes, and most people shot for 712 or so.
Not anymore. I'm working on a new site (code name: Peter's New Site), and doing the first bits of design, and am now free to go wider! The vast majority (over 90%) of US visitors now have their screens set to 1024*768 or 1280*1024. My statistics package agrees with other posts I have found around the web that says only around 7% of people are using 800*600 now.
A little geeky of a post, I know :-), but just more info for you.