I couldn't find an existing thread to bump, but this is a critical step in your ownership if you want warranty services or if you want to add the additional Microsoft Complete Extended Service insurance to your new Surface--this must be purchased within 45 days after buying your Surface if you want it. People who bought from other vendors like Best Buy are qualified for the MS Complete warranty (thanks hypokondriak!). The serial numbers are on the stickers on your boxes. Posted from a different thread: Hopefully others won't see the weird login issues I was having--my desktop IE10 for the registration URL went to a completely blank "login.live.com" address, and while I could log in fine with my Opera browser, the form field for the serial number didn't work at all. Maybe other browsers work, but after trying twice (on MS's IE10 no less), I just went for IE11 on the Surface. Edit to add: The reason for this roundabout business is because the normal registration page does not yet include the second generation Surface stuff in the drop-down list.