Sql 2008 Instance in SQL 2005 Clustered Server

Is it possible to install and run SQL Server 2008 instance in the Windows 2003 Server which is already installed with SQL Server 2005 (Clustered)?
Regards,
Mani

Yes it`s possible but the challenges you might face is performance and sql version conflict`s issues, but why would you want to do that. I think it would be better if you run sql2008 upgrade advisor and just upgrade both your instances since they are in a cluster. But carefully study the upgrade advisor report, you dont want to regret if your boat sails away without you.
To be save you can firstly test this on a virtual environment.

You can install stand alone but what are trying to do?