>Of course you don't have to... until you want to use your credit card at some URL that is supported and supports passport, or your subscribe to an msn service.
>Besides, when the GUID info funnels back to MS they'll have it anyway.

Big Brother isn't watching you. He doesn't need to, and he doesn't care. He's just watching what you do and what you may buy... or at least what you may be charged for.