I hate how it’s actually not possible to update your xbox account with a different Windows Live ID (formerly known as Passport account) than the one you first used when you signed up for Xbox Live. I bought one of the original Xboxes when they first came out which was well before Windows Live Custom Domains (now known as Windows Live Admin Center). Since that service has been available I’ve been using that account for everything-except, unfortunately, on the Xbox. This means I maintain two separate accounts of Microsoft Points, can’t really use Messenger on the Xbox as it’s not the account I have my “buddy” list on, etc. A little grumpy about this, hopefully it’ll change someday.

Update: Looks like the change is already underway. See the links that “mga” kindly posted in the comments below for more information. I’m no longer grumpy. :)