For those who haven't worried about patching their OS for two and a half years, the old antispyware version of Defender strikes me as a rather lame reason to suddenly become interested. I have advised against using Defender for years, notably in the 3-year-old thread
Avast Turns Off Defender. I also doubt that definition updates will continue after support for Windows 7 ends on January 14.
According to the text files that Microsoft deliberately includes with Windows updates, virtually all Windows 6.0 updates released in recent years apply to both Windows Vista SP2 and Windows Server 2008 SP2. For example, I just extracted this document using 7-zip:
VistaLover of
MSFN has just shown that definitions for Defender can still be installed:
Server 2008 Updates on Windows Vista.