Take control of system protected files in Windows 7

For Files:

takeown /f file_name /d y
icacls file_name /grant administrators:F

For Directories (will perform action recursively):

takeown /f directory_name /r /d y
icacls directory_name /grant administrators:F /t

http://www.blogsdna.com/2166/how-to-delete-undeletable-files-in-windows-7.htm