Control Panel User Accounts shows my name as administrator. When I try to Format C: under Command Prompt it still comes back with "Access denied-insufficient privileges".
If you use UAC, then all programs run without any privileges even if you sign on as an administrator. If the program isn't flagged as requiring administrative privileges or if it doesn't request those privileges when it runs, then it doesn't get them.
If you want to perform tasks that require privileges from within Control Panel, you have to right-click it and use the "Run As Administrator..." option. The same applies to PowerShell.