I found some cute software called BloGTK which allows me to post to practicaluseful.com right from my Linux desktop.
Assuming this post works then the correct account settings to get it to work with WordPress 1.5 and above is:
Server URL: http://yourdomain.com/path_to_your_blog/xmlrpc.php
Account: Your Username (admin?)
Password: Your Password
Blogging System: Moveable Type