Disaster Recovery Site For SQL Server 2005

Dear Brothers; We are planning for the disaster recovery site for our SQL 2005 cluster , we have two nodes cluster active /active in our main site , I’m thinking of upgrading the OS from Compute Cluster Edition to Windows server 2008 so I’ll be able to cluster over different subnets, without the need for geo cluster.
Can you help me with your experience with upgrading the OS of an existing SQL cluster, and any recommendation you may have, Thanks