Arbasoft AD,
i would your question your approach towarnig accomplishing high availibility with three nodes, this solution does not make much sense to me. and there is no documentation to accomplish that. can you please share your motive behind 3 nodes
2007 uses a clusteredmailbox that revolves around nodes... there are no virtual servers as they used to be in earlier versions
so there will be one active node. and other two may be left passive. i would say this would be heck of waste of resource
so go by two nodes.
Thank you