Solution to the SQL Server 2008 with Visual Studio 2008 SP1 Install Exception: "SQL Server 2008 setup requires .NET Framework 3.5 to be installed"

You would have never guess this by the error message, but “”SQL Server 2008 setup requires .NET Framework 3.5 to be installed” when you have Visual Studio 2008 SP1 installed means that you need to install Windows Installer 4.5, which can be found here:

http://www.microsoft.com/downloads/details.aspx?FamilyId=5A58B56F-60B6-4412-95B9-54D056D6F9F4&displaylang=en#filelist