Windows Live Writer is an interesting tool - MS is trying to keep the desktop relevant, I guess. It certainly is a more "natural" feeling interface for writing than, say, Performancing's Firefox extension.
Though the default is to use Live Spaces, it appears to have downloaded my blogger css file and is using that to create a true WYSIWYG environment. Very Clever.
Updating a previously published post is also as simple as can be. Just open the post and type.