Believe it or not, Microsoft’s 
Windows Live Writer is important in more ways than one. To most PC users, Windows Live Writer is simply the best tool that gets the “job” done. More importantly is how “job” is defined though, because WLW does things quite well and quite thorough.
Windows Live Writer has a huge range of options and takes advantage of almost all the features and functionality available via remote blogging/XMLRPC that make it almost pointless to even enter your blog’s administration center. You can upload images and movies, set categories and keywords, specify the slug/permalink to posts, modify the post date, set passwords on posts, send trackbacks, manually create an excerpt, and even specify whether comments are or aren’t allowed on any given post – all this without leaving your desktop client.
But what most don’t know about Windows Live Writer is more what it represents than what it does: Windows Live Writer is the first full-scale consumer product to ship out of Microsoft’s camp built on the .NET Framework.