So far, IE8 and below lack support for HTML5 elements. In fact HTML5 elements won’t render at all in those versions (hopefully IE9 will fix this). An HTML5 template will look pretty silly in IE8 and below, but there’s a way to fix that.
I was asked by one of my readers to define the difference between floating elements and inline elements, vis-a-vis, display: inline v.s. float: right or float: left.
Internet Explorer tends to render code deformedly due to its disregard to web standards. Thusly, there’s a problem with the way your website looks in IE; you need to target specific code to IE in order to apply a fix.