Microsoft Cluster Configuration Tool
I just noticed that the Microsoft Cluster Configuration Validation Wizard was released yesterday. Don't bother about the long name, everyone just calls it ClusPrep. This is a great little tool that will evaluate potential nodes that are to be clustered. You can also run it on existing clusters for inventory purposes of you cluster. It currently is not supported on Vista so you will have to install it on Server 2003 or XP to do your testing.