I have a proposal to consolidate two Sql clusters into one. Both clusters use two instances of Sql Server 2000 running on two nodes in Active-Active config each, but the new cluster will have two nodes with two instances runnig on each node. The new servers are a lot better perfomance wise considering RAM and CPU. The problem is that I can upgrade only two out of four Sql Servers to Sql 2005. Just wanted to put it out there before I start testing on it. Does any one know or has encountered any issues with running Sql 2000 and Sql 2005 on the same cluster and same node. I plan to run one Sql 2000 and one Sql 2005 instance per node. The OS will be Windows Server 2003.