www.get.live.com
www.msgpluslive.net/download
Always download WLM from there and make sure you always download MP!L from the second link (it will always be the newest version). You should not be getting messages to upgrade from 8.5 yet at all so that was either
a) you read the message wrong
b) a possible server error
c) a malicious version of the program taking you to a dangerous website.