Nancy,
I tried this approach with using my live account, except now, when I go to my Office 365 email or teamsite in a browser, it starts to open, then defaults to opening the email client for my @live.com account with all the ads and junk I don't want. And the only way it seems I can get back to my Office 365 stuff is to log out of that email window, and then go back and open my Office 365 site again. I have to do this everytime I login to my machine.
It would be great if we can use our Office 365 accounts as a Windows 8 login. Seems like a really big oversight by Microsoft.