>I need to install Reporting Services on a Windows Server 2003 cluster which already has SQL Server 2005 installed. I have been told that to do this I will need to uninstall SQL from the cluster and re-install it with RS. This is a production server. It would be much preferred if RS could be added without a complete uninstall. Is this possible?

It's always a good idea to ask "Why?". See if http://serverfault.com/questions/74963/configuring-reporting-services-sql-server-2005-in-a-failover-cluster-windows-serv helps.