If you need to install a SQL Server 2005 instance on a cluster, make sure that there aren't any remote connections to any of the other nodes. Otherwise, the installation may fail with the following error:
Setup failed to start on the remote machine. Check the Task Scheduler event log on the remote machine.
Please refer to this Knowledge Base article for more information.
I get this error every now and then and usually can't remember how to resolve it. Maybe I'll be able to find my own blog entry when I search on the error!