I recently updated to windows 7 pro from vista home premium. My laptop has two hard drives, C (w/ 30 gb and D (w/ 180 gb). Vista came on my C drive but I installed 7 on my D drive because it had more space. Now though my C drive still contains the Windows folder from Vista and it's taking up 20 gbs while the new Windows folder for 7 is only using 7 gb on D. I already deleted the windows.old file that came from the 7 installation but whenever I try to delete the Vista Windows folder on C I get a message saying I need permission from trustedinstaller. How can I get rid of the vista files because they are taking up way too much space?