I'm writing a small intranet app that uses Windows Authentication and Asp.Net MVC. I need to store various bits of data in a db against each user. As far as I can tell the IPrinciple object does not seem to have something like a unique id. So I was thinking I could just use User.Identity.Name as a unique value to identify rows in my db. Is this a bad idea? Is there an alternative to this approach?

Thanks for any help.