You're welcome! Mackb
I ran into something similar lately between two installations of the 64bit RC where the read only box wasn't the only thing it took to see the Windows.old folder removed. But that was from the multibooting done here mostly.
First the last sub folders had to be removed one at a time until eventually the ownership could be taken for that particular one time problem. Once you have administrative access for any new installation of Vista or 7 you simply uncheck the box, click the apply button, and call it a day!