IE traditionally drawn a 2-pixel border around the content area of a site. "This border, drawn as part of the page rather than IE's frame, affects calculations of distance from the top and left of the page. It also creates a not-so-modern beveled look. But no more, in the IE9's 4th Platform Preview, you'll notice pages running in IE9's Standards Mode no longer have border," informs Microsoft:
"Pages that run in legacy document modes will still have a 2-pixel border so that any site calculations dependent on 2 pixels remain the same as in IE8. To make sure your site runs in IE9 Standards Mode and gets this and all other latest features in IE9, use a HTML5 doctype (<!DOCTYPE html>) since it's simple and will put your site in Standards Mode in all current browsers," explains Microsoft.