Very comprehensive - vSphere 5.5 is compatible with various versions of: Asianux, Canonical, CentOS, Debian, FreeBSD, OS/2, Microsoft (MS-DOS, Windows 3.1, 95, 98, NT4, 2000, 2003, 2008, 2012 incl. R2, XP, Vista, Win7, 8), Netware, Oracle Linux, SCO OpenServer, SCO Unixware, Solaris, RHEL, SLES and Apple OS X server.