Support Policy for Windows Automatic Update
Windows Automatic Update (WAU) is supported on a Cisco Unity 4.
http://www.cisco.com/en/US/products/sw/voicesw/ps2237/products_device_support_table09186a0080531aab.html#wp64185
Configure WAU only to check for updates, not to install updates. Most Microsoft updates can be installed on the Cisco Unity or Bridge server as soon as they become available. However, Microsoft service packs must be qualified for use with Cisco Unity and the Bridge, and WAU does not let you distinguish between service packs and other updates.