[quote name='whiptcracker']Did you have your 360 on and logged into Live when you did so? That's the mistake I made at first.[/quote]
Yup. I was sitting there with my 360 on, reading the codes off the TV, typing them into the activation page on my laptop.
It kept saying the code was not valid, so I clicked the "get a new code" button the 360, entered that new code, didn't work, rinse, repeat. I even tried using IE instead of FF, but that wasn't the issue.