Vista - Contact List crossover

For the last month I've been going nuts because I kept having to delete
contacts in Windows Mail that said "Name Missing" followed by a name only to
repeat it over and over again. I'd go to the contacts folder and find a
folder that kept coming back after I deleted it. I just figured out tonight
that it comes back when Windows Messenger signs in and consequently that
it's the contact list for Messenger. I also just figured out about the Name
Missing thing.

The problem I have is that my email and messenger lists are different and I
don't want them merged into one list when I go to send an email. How can I
prevent this from happening? I don't want the messenger contacts to show up
at all in my contacts list. What are my options, short of removing Windows
Live Messenger?