Which desktop operating systems are you familiar with?

Windows 7,8,8.1,10, XP, Vista and MAC OS X

iOS, Unix, all Windows platforms (win xp,win7,win8,win10,win server2003,win server2008,win server2012) ,

I used to Windows 7,8,8.1,10, XP, and Vista.

windows OS (all versions), Linux 

All windows Operating systems

I am familiar with Windows 7 and 10 and the now obsolete Windows XP.

I am familiar with Windows XP, Windows 7 and Windows 8 operating systems

 Windows 7 and 10 and the now obsolete Windows XP.

all windows versions plus mac (beginner)

MAC, Windows 7,8,10,XP and Vista

Microsoft Windows (Server + Client) and Ubuntu