Please add 2-step verification as an option for securing my xbox / windows live accounts. Many large companies have these systems in place and it should be offered to help curb account piracy. Using text messages or even a free verification application download on Windows Phone 7 / Android / Apple products would save your technicians a mountain of calls.
Similiar systems -
Google - http://googleblog.blogspot.com/2011/02/advanced-sign-in-security-for-your.html
Blizzard - http://us.blizzard.com/support/article.xml?locale=en_US&tag=TOKENFAQ&rhtml=true