Here's a quick checklist before you install an instance of SQL Server on a failover cluster; or any service pack or hotfix for an instance. Following this list should eliminate 90% of the most common causes of setup failure.
Please note that this checklist does not cover all the 'normal' requirements for installation of a SQL Server failover cluster instance. For that you may refer to this excellent white paper on the subject. I also recommend that you view my colleague Uttam Parui's webcast as well prior to attempting any installations on Windows Server 2008. He covers many issues specific to Windows 2008 as well.
Common points for all SQL 200x versions
The idea is to have the public network as the highest in the binding order.
The idea here is to make sure that the private network only carries internal cluster traffic and that it is listed as the #1 preferred network to carry that traffic.
Refer to http://support.microsoft.com/kb/258750 for this and the previous point.
Reference: http://support.microsoft.com/kb/283811, http://support.microsoft.com/kb/840219 and http://support.microsoft.com/kb/254321
SQL Server 2005 specific points
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