Also another quote from another source:
About PlayReady PC runtime (from Microsoft)
“Microsoft PlayReady technology is optimized for the mobile industry to support the growth of online content services, and includes features designed to make it easier than ever for consumers to enjoy mobile digital entertainment. This runtime allows PC based applications to access PlayReady content using the PlayReady PC Runtime API. Windows 7, Windows Vista with Service Pack 1 and above, or a 32-bit version of Windows XP with Service Pack 3 is required for installation.”
Do you need it ?
No. You can uninstall it if you want.