Tony has a Windows 7 laptop and he wants to replace the hard drive with an SSD and then dual boot with Windows 10. Leo says it's completely doable. Leo recommends backing up his data and then replacing the drive. Then he can do a clean install of Windows 7, and then do the Windows 10 upgrade. Then he can also choose a dual boot option.
There are a few pitfalls doing this, though. Leo recommends Googling "Windows 10 dual boot" for tips.