Surface Pro Windows 8 allows users to other OS like Windows 7 with double-boot system on the tablet. Surface doesn’t include a CD/DVD optical drive, so you have to use the bootable USB drive to install Windows 7.
* USB Flash Drive with minimum 4GB free space,
* Official Windows 7 ISO file from your Microsoft Store Account or your custom file.
How to Create Bootable Windows USB To install Windows 7 on Surface Pro
* Download Windows 7 USB/DVD download tool from microsoft website and install on your computer. Conect your Flash Drive to PC.
* Run the program, click “Browse” button to the Win 7 iSO source file > Next > USB device > select your media type from the drop down list, and then click “Begin copying”. The process will take a few minutes.
* If you get the error “Invalid ISO File. The selected file is not a valid ISO file. Please select a valid ISO file and try again.” during the above steps, use PowerISO (full version) to open your iso file, click File> File properties > Check UDF, hit OK and save the file.
Once the procedure is completed, plug-in your USB flash drive to Surface Pro’s USB port. Reboot the tablet and start installing Windows 7.