If you are getting a permissions related exception from the Team Project Creation Wizard even though you have added the user to the Team Foundation Administrators group, make sure the the user is also a Content Manager in Reporting Services.   This happened to me when I created a secondary user who was different than the user who installed the system, and then made that secondary user a Team Foundation Administrator.  I've got a bug logged to make the PCW (er, Project Creation Wizard) catch this situation and warn the user, so hopefully it will be smoother going forward.