SQL Server 2005 Developer Edition has the same feature set as the Enterprise Edition but different licensing policies.
See if http://support.microsoft.com/kb/934164 can help.

>I am wondering if Reporting Services is available to be installed from within the SQL Server 2005 Developer Edition? Or does it have to be the Enterprise Edition? The reason I ask is because the check box for reporting services is not able to be checked, which leads me to believe it is somehow unavailable. I am speaking of the 2005 Developer Edition of SQL Server.
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>Hwoever, on the below web page Microsoft says that Reporting Services is available. is there a change from 2005 to 2008?
>http://www.microsoft.com/sqlserver/2008/en/us/developer.aspx