I was grandfathered in to accessing Hotmail via HTTP mail, but when I bought a new computer with Vista, I couldn't add my Hotmail account to Windows Mail.
Microsoft announced recently that it has opened Hotmail to POP3 access by email programs and posted instructions for adding Hotmail accounts to Outlook Express on this page.
However, I couldn't get it to work with Windows Mail. I came to realize that Microsoft had put a hook in Windows Mail to prevent users from trying to add any Hotmail account using any kind of access.
I devised this workaround: set up a new email account in Windows Mail and specify any standard domain name EXCEPT hotmail.com. Use the defaults for Hotmail POP3 access as given on the instruction page linked above, but do not ask Windows Mail to test the connection. After the account is set up, go in and edit the email address to hotmail.com. Voila, it works. Hotmail will still follow your settings for junk mail, so you may need to check your junk mail folder online at an appropriate interval for false positives.