First check your version of Ansible as some older version may have had some bugs with spaces in paths.
I'd think you need to quote around the path itself. using strict yaml i think ive done it
dest: 'C:\Documents and Settings\All Users\Start Menu\Windows Update.lnk'
or if you go with doublequotes, i think you may need doublslashes like
dest: "C:\\Documents and Settings\\All Users\\Start Menu\\Windows Update.lnk'"