If your hardware meets the requirements and you want to proceed, you also have to buy a copy of Windows 10, which costs $120 for the home version. The computer also needs 16 to 20 gigabytes of hard-drive space and a DirectX 9-compatible graphics card running the WDDM 1.0 driver software. At the very least, the PC must have a one-gigahertz processor and one gigabyte of memory for the 32-bit version of the system (or two gigabytes for the 64-bit edition). To go the less expensive route, first make sure your computer meets the Windows 10 system requirements, which are listed on Microsoft’s website. If you are interested in moving from Windows Vista to Windows 10, you can get there by doing a time-consuming clean installation after buying the new operating system software, or by purchasing a new PC. The free Windows 10 upgrade is available only to Windows 7 and Windows 8.1 users until July 29. Windows Vista is not mentioned in most articles about updating a computer to Windows 10 because Vista is not included in Microsoft’s free upgrade offer for the new operating system. My somewhat ancient Hewlett-Packard laptop is running Windows Vista, and I never see Vista mentioned in articles about upgrading operating systems.