Unless you are employed by Microsoft it is impossible to have a @microsoft.com
email address.
The email program that is included with Vista is called Windows Mail, not
Outlook Express.
If you have a Hotmail.com email address, Microsoft recently enabled POP access
for free Hotmail accounts. Follow the settings given here:
http://mailcall.spaces.live.com/Blog/cns!CC9301187A51FE33!49799.entry
Use port 587 rather than port 25 for the SMTP server.
Windows Mail's new account wizard is hard-coded to reject Hotmail
and MSN addresses. So, when you enter your email address initially,
use a fake one, such as (e-mail address removed). After the account setup is
complete, go back and correct your email address.