Hello thuntert, go to a hub computer, open One Care>Manage Your One Care Circle, find the deceased computer and select "Remove this computer". To install One Care on the new computer, download the trial - http://onecare.live.com/standard/en-us/3/default.htm
To activate, open One Care, select "Subscribe" and when asked for a Live ID enter the Live ID and password associated with your One Care subscription, your subscription status will be recognized and One Care will activate.