Actually, I included it here to demonstrate the additional markup required to contain the clearing div. Clearfix is better contained, and uses less markup.

One thing about IE and floats: position:relative property applied to the selector with the float property makes all kinds of problems go away, including the phantom width problem.

You might be able to remove the float from the header by giving the header a fixed height and relative position, then absolutely position the two float items, logo and RSS.