HTTP access to Hotmail will be ending June 30, 2008. While the following article is specific to Outlook Express, Outlook also uses WebDAV when it uses the HTTP protocol. Users will need to install the Outlook connector for Outlook 2003/2007 or use Windows Live Mail client if they want to continue to use an email client with Hotmail.
Microsoft Announces Changes for Accessing Hotmail with Outlook Express
http://emailsupport.spaces.live.com/blog/cns!5D6F5A79A79B6708!5359.entry