Jun 28, 2013 - 03:27 PM
No, it won't hurt your computer. When you reinstalled the operating system windows made the old windows folder windows.old. This is so you can move any files you had in the old folder over to the new one.
In order to delete the old folder click on the start button and then computer. Then right click on local disk (C:). From the drop down box click on properties. Now click on disk cleanup. Click on files from all users on this computer. After scanning another dialog box opens and you'll have a list with check boxes. Scroll through and check the box that says older versions of Windows. Then click OK. It should then delete that folder.