Take Ownership of System files in Windows Vista

It always happens, even in Windows XP... you need to move or delete some files, but Windows gives you an error that you need permission or that the file is in use. When tweaking your Vista system, you will probably need to modify some system files, but Vista has this locked down tight. You can take ownership of any file in Windows Vista, and then grant any username full control of the file. After you have made your modifications, you can then remove the permissions, setting the file back to its original state.

Check out the guide at OCModShop.