Comment Nmap 4.85BETA5 just released (Score 4, Informative) 288
I'm happy to report that we've just released Nmap 4.85BETA5 with Conficker detection so you can do that scan! The actual recommended command is:
nmap -PN -T4 -p139,445 -n -v --script=smb-check-vulns --script-args safe=1 [targetnetworks]
For more details, see the announcement at http://insecure.org.
-Fyodor