Guidance on upgrading RAM in a 2-node Server 2003 cluster

I cannot find any best practice/official guidance on upgrading RAM in a
2-node Server 2003 cluster (ENT R2 SP2 x64). We are operating a 2-node
cluster running MS Virtual Server 2005 R2 SP1 in active/active configuration,
with guest VMs running on each cluster node. We are looking to upgrade from
8GB to 16GB on each node.

We have implemented the MS Virtual Server guests following best practice,
with a generic script resource configured to restart the guest VM if it
discovers that the VM is not in a running state.

I had hoped to perform a 'rolling' RAM upgrade, but after upgrading one node
from 8GB to 16GB, I discovered that we were unable to move any VMs onto the
upgraded node - the generic script resource would fail with error 1233. So I
had to back out the RAM upgrade.

Is there any guidance or documentation available?