Systems sold within the first year of the release of Windows 7 had a Free Upgrade to Windows 7. These systems typically had a SMBIOS of 2.5. For these systems the OEM typically released a BIOS Update which updated the SLIC from 2.0 to 2.1 and this makes the system eligible for Windows 7 OEM System Locked Preinstallation. You can then install and activate Windows 7 32 Bit and generate a genuine ticket to activate a clean install of Windows 10 32 Bit. More details are about this are available Updating your BIOS in Windows Vista and Checking the SLIC Version. If the systems SLIC remains at 2.0 you can still install Windows 10 without a Product Key. This will leave your system unlicensed with it watermarked to the bottom right hand corner and you will be restricted when it comes to some settings but otherwise it is fully usable and more functional than Windows Vista. It will also be patched and be safer to use online. See Windows OEM FAQs and Downloads for more details on clean installing Windows 10 Home 32 Bit (note when making media this system will be a Legacy System).