First of all, why would you have 4 email programs on one computer? Not to mention, that 3 of them are the same program, just different successive versions of it.

I'm positive that Windows Mail uses Vista's built-in contacts thing, as I've seen contacts created by something in there, and I've never created a contact for anyone on my computer or ever stored anyone's address/email/phone #.

Now, Windows Live storing its address book somewhere seperate than the Windows one makes a bit of sense as isn't it stored in your online profile? At the very least, it could other an option to sync up the two, to put all of your Windows Live addresses in with your Windows addresses and vice versa. But, even that is problematic, as if 2 people use Windows Live * under the same user account, then you will end up with their contacts as well.