If I have a 32 bit system and a 64 bit system connected to the same SAN, can I create a cluster between them?
No, you can't with Windows Clustering - you wouldn't get as far as being able to put the two nodes in the same cluster, let alone run SQL Server on top of them. See here.
However, you would be able to using some third party clustering solutions, Veritas Cluster Server being one of them.
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