Hi bkg16,

Currently there is no option to download the operating system from Dell support site. Dell does not provide the operating system disc as there is inbuilt utility called ‘Dell Backup and Recovery’ which helps in restoring the system to Factory state. You can create a recovery discs on the new computer so that you can restore the system to factory state in future with the original hard drive shipped with the system. Please follow the steps mentioned below to create recovery discs.

1. Point to the right of the screen and when the charms bar comes up, click Search then type in Dell Backup and Recovery. Click Dell Backup and Recovery.
2. Click the Reinstall Disks tile.
3. Click Factory Backup.
4. Select either USB Flash Drive or Discs as per your requirement. Ensure to connect the USB Flash Drive or put blank media into the optical drive.
5. Click Continue.
6. Click Start.
7. The factory image is created on the USB flash drive or disc, click OK once done.
8. Also, you can create recovery discs for ‘OS Media’ and ‘Apps & Drivers’
9. Please make sure the media you have created is kept is a safe location for future utilization.

Please let me know if this helps.

The Windows 8.1 .iso can be downloaded from Microsoft, providing its not a Bing Edition. You need to ensure that you select the same Edition as preinstalled as the various Editions are not interchangeable:

http://dellwindowsreinstallationguide.com/download-microsoft-windows-and-office/download-microsoft-windows/download-windows-8-1-retail-and-oem-iso/