In the US, you can request it here: support.dell.com/.../backupcd_form Alternatively, you can download and install using "retail" media, then activate over the phone (with Microsoft, not Dell) using the Product Key on the COA/license sticker on your system: www.mydigitallife.info/windows-7-iso-x86-and-x64-official-direct-download-links-ultimate-professional-and-home-premium
How can obtain installation disks from Dell for Windows 7 factory installed O.S. ?  Cannot get through on support web site without a customer id, no chat or e-mail options to find out this information. Must have an order i.d. or a customer i.d.
How to aquire installation disk from Dell for a factory installed Windows 7 
Operating System?