Is it possible to install SQL Server Express 2005 SP3 on Windows 2008 Server R2? If so, is there anything special that needs to be done to get it to install properly? I ran into some issues with the installer and wasn't sure if it could be installed with 2008 R2.
Microsoft SQL Server 2005 Service Pack 3 and SQL Server 2008 Service Pack 1 and later versions are supported. SQL Server 2005 Express Edition Service Pack 2 and SQL Server 2008 Express Runtime RTM are also supported. SQL Server 2008 R2 will be supported in H1 2010.
As to why you can't install it, you need to provide more details on what you're experiencing before a cogent answer can be given.