I kept getting a Failure while applying Microsoft SQL Server 2005 Service Pack 2 today for 'Database Services' and 'Analysis Services'. It was a brand new installation so I couldn't think of anything that would cause this. I found a kb on Microsoft's site that fixed the failure for 'Database Services'. I'm still getting the failure on Analysis Services. I will update this post when I find the solution.
Missing your SQL Server Management Studio after installing SQL Server 2005? When creating my Microsoft Office SharePoint Server (MOSS) development environment I had the same problem. Thankfully, Pete Orologas posted a solution and it worked for me. Apparently, if there is already a \Program Files\Microsoft SQL Server\90\Tools folder that exists then the installer moves on to the next step. How does that subfolder get there? Well, if you install Visual Studio before SQL it creates the folder when installing SQL Express. Or if you install the SQL Express edition it will create the tools folder.
THE SOLUTION?
Rename the Tools folder to something...