http://thevistaforums.com/index.php?showtopic=13839
To take full ownership:
1. Right click file, select properties.
2. Hit security tab, select advanced
3. Click owner tab, the hit edit (accept the UAC pop-up box)
4. Select your username, click OK, accept the pop up box, then OK out of all dialogue boxes
To take full control
1. Right click file, select properties.
2. Hit security tab, then click on your username.
3. Hit edit, then click on your username on the pop up screen
4. Check the box marked "full control" under the allow heading
5. OK out of all dialogue boxes
Now you have ownership and full control of that file.
Download this file and install the TakeOwn+.reg file. After you have done that all you need to do is Right click + Shift on the file that you want to take ownership of and select Take ownership.
http://dazzy.org/vista/TakeOwn.zip