Reviews of Windows Live Writer are generally favorable, so I decided to give it a try. This post is being written with Writer.
If you want to try it, the first step will be to get a copy and install it on your own computer. This is easily done by going to the Windows Live Writer website and clicking on the Get It Free button.
The install process is typical Windows. Just accepting the defaults seems reasonable to me, except for where the installer gratuitously offered to change my browser Home Page and my default Search. I unchecked those.
The main advantage of Writer over just composing a post in the BlogEngine.NET editor is that Writer provides WYSIWYG (What You See Is What You Get) editing. It is a lot like writing in a simplified version of Word. The spell checker will surely come in handy as well.
A couple of points from the Writer website that will be useful are:
Preview before you post
Writer shows you what your blog entry will look like before you post it, using your blog's templates and formatting.
Compose your entries offline
Publish them later, when you get back online.
There are helpful getting started videos at the Writer Blog Site in the May 2008 section. I watched the first one.
I read somewhere that Word 2007 (but not 2003 or earlier) works well also, but Windows Liver Writer is free, and it appears to work just fine.