You may be able to get a .iso from Dell here: [URL]  See here for details: [URL]     
Hi All, My Dell Precision is selled with Windows 7 Pro OA operating system. But the disk is damaged, where and how can I download the original operating system? On the microsoft website when verify my OS product key displayed me go to the manufacturer page where I can do that. Exactly where can I download it?  Thank you in advance. 
Download original windows 7 pro oa