I came across this great resource from Google today. It shows the percentage of total visitors to your web page, that will see each part of your page content. One thing it clearly shows is the importance of having your key website content above the fold. To use it, visit http://browsersize.googlelabs.com/ and enter your site's URL and click the "Go" button. The percentages shown on the screen are the percentage of your visitors that Google estimates will see each section of your webpage. Have a look at Google Browser Size and please post back to let us know what you think of it.