I recently picked up a new machine and decided to run Vista. First thing I installed was Visual Studio 2005. Everything worked fine for a few days. I then decided to install a copy of SQL 05 Express Edition. Then I installed the x64 SQL Management Studio. At the end of the install I received an obscure error code "29506" and the Management Studio install rolled back. I then fired up Visual Studio 2005 to be greeted with a message saying I had to install Visual Studio 2005 SP1 for Vista(KB932232). I installed the service pack, rebooted the machine, then when attempting to start Visual Studio I would receive the error "The application cannot start".
At that point I was thinking a bad rollback of SQL Management Studio was the unlikely root cause and the more likely culpret was KB932232. After doing a repair of the Visual Studio install everything worked fine. I gave the SQL Management Studio install another go and received the same failure and rollback. Then again when attempting to start Visual Studio I would receive the error "The application cannot start". It was starting to look like the SQL 05 Management Studio Express x64 installer rollback was the cause after all. So I done another repair on Visual Studio.
To successfully install SQL 05 Management Studio Express we need to get around the "User Account Control" feature of Vista. Run a command prompt as administator by right mousing on the All Programs->Accessories->Command Prompt menu and selecting "Run as administator". Navigate to the directory holding the SQL Management Tools installer and run the MSI. The installation should complete successfully as administrator.
Now you should be able to start SQL Management Studio and Visual Studio 2005 on Vista cleanly. Without delving any deeper it appears the SQL 05 Management Studio Express x64 installer breaks something in Visual Studio 2005 on rollback.