I know that your question sounds simple, but I'm having a hard time with it. Perhaps you mean just what you are typing, in which case, yes... you can host a communication 2003 sever on just 1 server 2003 box. That question sounds extremely simple though.. Am I reading it correctly? And yes, having an IM and sharepont server dual role wouldn't be too bad at all. How many users are there in your topology?