Many laptops in the Dell Inspirion and Alienware series come with Windows 7 Pro installed and are available through Dell's website, as of 2015. These laptops include the Alienware 15, Alienware 17, Inspirion 15 and Inspirion 17.
Many laptops from Dell that come with Windows 7 Pro also come with a free upgrade from Windows 7 to Windows 10, as of August 2015. Dell also offers laptops that come with the Windows 8.1 and Windows 10 operating systems pre-installed. According Dell's official website, Windows 10 features brand new improvements to both the Windows 7 and Windows 8 operating systems to make using it easier than ever.