For your information, you DO NOT need a MSN/Hotmail email account to use MSN Messenger.

You CAN use your own email address to login MSN Messenger.

You just need to register a Passport with your own email address, then you can login MSN Messenger with the email.

Thoughts:
My friends are surprised that I use own email for MSN Messenger and they purposely register a hotmail account just to login MSN Messenger.