I was setting up a virtual PC instance of Windows Server 2008 and I ran into an issue when installing SQL Server 2005 on it. I got the following warning in the SQL Server 2005 setup wizard:

"Microsoft Internet Information Services (IIS) is either not installed or is disabled. IIS is required by some SQL Server features. Without IIS, some SQL Server features will not be available for installation. To install all SQL Server features, install IIS from Add or Remove Programs in Control Panel or enable the IIS service through the Control Panel if it is already installed, and then run SQL Server Setup again. For a list of features that depend on IIS, see Features Supported by Editions of SQL Server in Books Online."

I had IIS installed and running already, so I was puzzled. After some searching on the Internet I found out that the problem was that I didn't have all the IIS features installed that I needed.

This MVP blog post was helpful and lists all the IIS features that you need to have running before installing SQL Server 2005.