I can't guarantee anything, but take a look at the MS08_067_NETAPI exploit in Metasploit

Also, take a look at the other exploits in Metasploit. There is usually opcodes for most operating systems included in the exploits, so if it was me then I'd take one of them and try to use it.
There was another site which had a huge database too, but that's unfortunately down as well.

(Dead reference:
http://www.securityfocus.com/archive/82/445612/2010-08-29/1 )
I did try to find cached examples of that opcode list he had, but I couldn't find any.
If you ask him nice, and if you can find him, then "Jerome Athias" is the guy you need to look for about that opcode database I'm referring to. Good luck!
