Hi Frank
and thanks again for responding. I have really not much of an idea of what I'm supposed to do and this has been made a performance requirement for me, so I'm kind of petrified. 
I just need some reassurance that what I plan to do is the best possible way of doing it, with zero disruption to the existing system.
Thanks for the youtube link!
I'm supposed to use 3 servers to consolidate the 5 original hosts, and turn one into a disaster recovery server.
Please how is this done?
When I add the esxi 5.1 hosts to the esx 4.0 cluster, do I still have to setup networking and datastore access or does configuration get passed automatically?
I apologize for the silly questions, and I'm frantically reading all I can online.
Thanks again for listening!