Heh, Fun fact: The "Classic" Windows 7 style Desktop seems to be an app in itself. If you don't have anything else open, it's possible to drag it away and just get a blank green screen. Me thinks that's probably the real desktop, and the "desktop" app (as I'm now thinking of it) is this "WIndows 7 Mode" we were hearing about.
Also... Microsoft are a bit more clever than I give them credit for. I was concerned about not being able to logon if the machine isn't online, and your Windows Live account is being used as your logon. It just asks for the last password used on the machine.