Admin.exe: Installation of MSSQL 2008 on Windows 2008 R2
This message can be ignored. It just means that you need to install the Service Pack 1 later.
Afterwards the setup checks if all necessary software packages are installed. It will inform you that .NET Framework needs to be installed.
At this stage you need to cancel the setup because the setup would try to install the software. This try would end with an error message:
You must use the Role Management Tool to install or configure Microsoft .NET Framework 3.5.
This message is printed because the R2 edition of Windows Server 2008 is already equipped with .NET but you must activate it.
To do this you need to enter the Server Manager. Just type Server Manager at Start menu to launch it.
In Server Manager go to Features qnd click on Add Feature. Then you need to select the first option: .NET Framework 3.5.1 Features.
Please run and finish the wizard. Afterwards the SQL server setup can be started once again and there will be no more warning about missing .NET Framework.