If you want to create good multimedia applications for Windows, you need a solid API -- something like DirectX. It has you covered for PC games and for apps that use 3D animation, 2D graphics and visual effects, as well as audio playback and mixing. Microsoft developed DirectX 9 during the 2000s and, as of 2014, the most current version is DirectX 11. However, some developers still use DirectX 9 because DirectX 10 and 11 don't work on older Windows systems, including the still-popular Windows XP.
Minimum System Requirements
As a Windows API, DirectX 9 requires the Windows operating system and can run on a variety of Windows versions, including most versions of Windows 98, Windows 2000, Windows ME, Windows XP and Windows Server 2003. The hardware requirements are the same as for Windows itself: If your computer can run a compatible version of Windows, it can run DirectX 9. Windows XP, for example, requires a minimum Pentium 233 MHz processor, at least 64MB of RAM, at least 1.5GB of hard disk space and a CD-ROM drive. The minimum requirements for older versions of Windows are lower.