How do I take ownership of a file that I do not have access to?

Note: You must be logged on to the computer with an account that has administrative credentials.

To take ownership of a file, follow these steps:

1. Right-click the file that you want to take ownership of, and then click Properties.
2. Click the Security tab, and then click OK on the Security message (if one appears).
3. Click Advanced, and then click the Owner tab.
4. In the Name list, click Administrator, or click the Administrators group, and then click OK. The administrator or the Administrators group now owns the file. To change the permissions on the files and folders under this folder, go to step 5.
5. Click Add.
6. In the Enter the object names to select (examples) list, type the user or group account that you want to give access to the file. For example, type Administrator.
7. Click OK.
8. In the Group or user names list, click the account that you want, and then select the check boxes of the permissions that you want to assign that user.
9. When you are finished assigning permissions, click OK.

This information is taken from http://support.microsoft.com/kb/308421