|The volume name you can see in Explorer or my computer.|
Having said that you can't format your c: drive from Windows in administrative mode or any other mode, you would in fact be telling Windows to delete itself.
You do realise, formatting the drive destroys everything on it?
Do you have your instalation disks to reinstall Vista and all your programs?
To format your drive containing the OS you would need a bootable disk with the format command on it, like your Vista disk.