Before you let go of that Windows 7 machine, ensure you have checked these boxes:
If your computer came pre-installed with Windows 7 (from brands like Dell, HP, or Samsung), it likely has a hidden recovery partition that can restore the system to factory settings. How to Wipe hard drive on my Windows 7 computer? wipe drive windows 7
: Type list disk . Identify your hard drive (usually Disk 0). Select and Wipe : Type select disk X (Replace "X" with your drive number). Type clean all and press Enter. Before you let go of that Windows 7